Table of contents

Characterization and wide study of thermoluminescecne and photoluminescence response of a Y₃Al₅O₁₂ phosphor with Mn²⁺ has been reported here. Different concentration of Mn²⁺ activated Y₃Al₅O₁₂ phosphor prepared by the combustion method at 500 °C. Crystal structure of prepared phosphor were investigated by XRD and FTIR the optical properties investigated by UV–vis spectroscopy. The photoluminescence excitation and emission spectra band exist at 388 nm. The thermoluminescecne sensitivity observed when a wide range of UV excitation at 5, 10, 15, 20 and 25 min and after 15 min saturation occurred. Further detailed TL parameters kinetic order, activation energy and frequency factor calculated by the de convoluted curve. Therefore various study factors shows that Mn doped phosphor is suitable and compatible for the solid state lighting devices and may be dosimeter purpose.

Biogenic reduction of metal precursors to corresponding metal nanoparticle (NP) is growing interest among scientists. In the present study, we explore the use of common cheap apple, orange, and aloe vera juices for the synthesis of industrially important stable palladium (Pd) NPs in a rapid room–temperature method without using any external surfactants or capping agents. The formation of Pd NPs is confirmed by powder x-ray diffraction (PXRD), x-ray photoelectron spectroscopy, and ultraviolet–visible spectroscopy. Transmission electron microscopic images clearly show that the spherical Pd NPs have a uniform size distribution in the ranges of 2–25 nm depending on the type of juice. The Pd NPs obtained using apple (Pd–Aj) and orange juices (Pd–Oj) are more uniform and smaller in size than those obtained using aloe vera juice (Pd–Av). The sugars and polyols (with OH–groups) of the juices act as stabilizers of the Pd NPs as confirmed by thermogravimetric and Fourier transform infra–red analyses. Furthermore, the as–synthesized Pd NPs exhibit size−dependent SERS activities and are suitable for lower–level detection (10⁻⁶ M) of environmentally harmful methylene blue dye in water.

Effect of size on carrier dynamics in CdS nanoparticles (NPs), synthesized by chemical evacuation with thiophenol as organic stabilizer, have been studied using steady state Photoluminescence (PL) and Picosecond Time-resolved Photoluminescence (TRPL) measurements. An enhancement of the NPs PL intensity when increasing temperature up to100 K, together with a distinctive thermal red-shift of the CdS-related PL peak emission have been demonstrated. These behaviors indicate the thermally activated carriers' redistribution between CdS NPs with different size. The low temperature PL decay curves of CdS NPs recorded at different emission wavelengths show that two recombination paths of the excitons with significantly different decay rates exist at high emission wavelength corresponding to the large NPs size (LNPs). However, as decreasing the NPs size, the dynamic of carrier becomes mono-exponential indicating a strong competition between the transfer and radiative recombination for the carriers inside the small NPs (SNPs). These results can provide useful information for fabrication and investigation of CdS NPs for implementing solar cells applications.

A one-pot synthesis of palladium nanoparticles (Pd NPs) supported on polycarbosilane (PCS) nanowires, which also served as reducing agents, was conducted using wet and dry processing methods. Relatively small Pd NPs with diameters of approximately 2 nm and narrow size distributions were directly formed along the nanowires without aggregation owing to the on-site reduction of Pd ions. In particular, the supported Pd NPs prepared from Pd(II) acetylacetonate vapor through dry processing at a temperature of 180 °C exhibited a higher number density as compared with that of the Pd NPs fabricated through wet processing. In addition, the catalytic activity of the obtained Pd/PCS nanowires for the oxidation of CO was evaluated up to 200 °C. The CO molecules were completely converted to CO₂ in the presence of Pd/PCS nanowires even at temperatures below 120 °C.

Optical properties of the Double Split Ring/Square Ring nanostructurre are investigated by using finite element method. Electric and magnetic resonances at optical frequency can be induced by this nanostructure. The symmetry of the structure is broken by adjusting the arm length of the double split ring and the offsets of the square ring, which leads the changing of inductance and capacitance. New magnetic resonances can be achieved and enhanced. Fano resonances are produced by the overlapping interference between bright electric mode and dark magnetic mode. The nanostructure allows the generation of multiple magnetic Fano resonances and strong magnetic field enhancement, which has potential applications in plasmons propagation with low-loss magnetic and multi-wavelength surface enhanced spectroscopy.

Suspensions of HA nanoparticles were prepared in different alcohols using triethanolamine (TEA) as dispersant. Optimum concentration of TEA increased with molecular weight of alcohol: 0.67, 0.67 and 8 ml L⁻¹, respectively, in methanolic, ethanolic and butanolic suspensions. Current density increased during EPD from TEA containing methanolic and ethanolic suspensions due to desorption of H⁺TEA ions from deposited HA nanoparticles under the influence of applied electric field. Particles were detached from deposits into the suspensions at the interface after switching off the voltage due to the generation of an electrochemical potential difference there. The rate of detachment decreased continuously in all methanolic suspensions and ethanolic suspensions with 4 ml L⁻¹ ≤ TEA due to the continuous reduction in the electrochemical potential difference at the interface caused by the effective diffusion of high concentration of free TEA and H⁺TEA species present in the liquid phase of deposits into the suspension. However, the rate of detachment remained constant in ethanolic suspensions with TEA < 4 ml L⁻¹ and in all butanolic suspensions. The mass flow of TEA and H⁺TEA species from deposit into the suspensions is negligible in these suspensions so that the electrochemical potential difference and so detachment rate remain constant.

The formation of an unknown superstructure with a 2a × 2a (where a is the lattice constant of the normal phase of 1T-TiSe₂) long period in multilayer 1T-TiSe₂ with a thickness of approximately 200 nm is induced at 296 K by electron beam irradiation during transmission electron microscopy (TEM). Since this superstructure remains unchanged even at 673 K, its formation mechanism cannot be explained by the known charge density wave phase transition of 1T-TiSe₂. Electron energy loss and energy-dispersive x-ray spectroscopy indicate that the formation of the superstructure also cannot be attributed to chemical reaction with the ambient atmosphere. Based on scanning TEM, the superstructure is considered to be formed by the periodic distortion of the Ti atomic position in multilayer 1T-TiSe₂ due to the electron beam irradiation.

Rod-like morphology of tungsten oxide (WO₃) nanostructures were successfully synthesized via simple microwave irradiation method for three different irradiation times. The Precipitation was obtained from a sodium tungstate salt solution and subsequent Microwave irradiation along with that furnace heating have been used to prepare the WO₃ nanostructures. Further investigation shows that monoclinic and orthorhombic crystal structures with a well-grown rod-shaped morphology of as-synthesized samples which were confirmed by XRD and HRTEM analysis. The optical absorption was measured by UV–vis spectroscopy and its band gap was calculated as the average value of 3.58 eV. The functional group linked with WO₃ was studied by Raman spectroscopy and confirmed the associated groups with WO₃. Finally, the suitability of as-prepared nanostructures for electrochemical supercapacitor was investigated by Cyclic Voltammetry (CV) and Galvanic Charge-Discharge (GCD) analysis, which revealed their highest specific capacitance 44 Fg⁻¹ at a current density of 0.5 Ag⁻¹.

The principal carbon nanotubes synthesis processes also involve the production of nanoparticles with different dimensions and morphology. In this research carbon nanotubes and carbon nanobeads were synthesized by one-pot chemical vapor deposition method, using a quartz experimental reactor at 760 °C. Benzene was used as carbon source, ferrocene as catalyst and argon as carrier gas. The obtained samples were separated in two parts according to their deposition zone. The nanostructures were analyzed through field emission scanning and transmission electron microscopy, energy dispersive spectroscopy, Raman spectroscopy and x-ray diffraction; all samples have high carbon content (above 92 wt %). Results demonstrated that the samples from the inner reactor present a predominance of nanobeads with higher crystallite sizes and degree of crystallinity in contrast to the carbon nanotubes found on the substrate surface.

In order to synthesize the gold nanoparticles (AuNPs) with uniform size and good morphology, two active disturbance systems based on surface acoustic wave (SAW) technology are presented and employed in the third stage (growth stage of crystal nuclei) of AuNPs liquid-phase synthesis. Through the optimization of SAW device, two kinds of SAW disturbance systems were designed and manufactured. For the orthogonal type SAW disturbance system, the concentration of synthesized AuNPs is the highest at V_pp = 5 V, but the size deviation of nanoparticles is a little larger. Meanwhile, for the rotary type SAW disturbance system, the concentration of synthesized AuNPs is significantly higher than the concentration of AuNPs synthesized in the orthogonal type SAW system. Moreover, the AuNPs synthesized by the rotary type SAW system are with more regular morphology and better monodispersity at V_pp = 35 V and f₀ = 50 MHz. Therefore, rotary type SAW disturbance system has a better perturbation effect for the controllable synthesis of AuNPs.

Stability and hydrophilicity of TiO₂ nano-coating was improved in this work. TiO₂ nanoparticles were prepared via conventional, microwave radiation, surfactant, refrigerating, and silica-assisted sol-gel processes. The coated rock plates were obtained by impregnating the plates with nanofluids. The modified TiO₂-based coatings shows to be more effective for wettability alteration purposes compared to the conventional TiO₂ coating. The un-coated surface was superhydrophobic where the n-heptane and water droplets contact angles on the rock surface were 0° and 168° respectively. The n-heptane contact angle on the rock treated via conventional, microwave radiation, surfactant, refrigerating, and silica-assisted sol-gel synthesized nanoparticles changed to 128°, 159°, 156.8°, 151° and 163° respectively. While water contact angle was 53.5°, 0°, 24.1°, 28.6°, and 0° applying the above processes. This confirms that the superhydrophilic coatings were formed on a superhydrophobic surface. The fabricated nano-coatings exhibited high thermal, mechanical and salinity stability. The rock surface before and after treatment as well as the synthesized nanoparticles were characterized by SEM, XRD, and FTIR analyses. Moreover, the surface charge of the nanoparticles in the solution was evaluated using Zeta potential analysis. Applications of these nanocoatings vary from self-cleaning surfaces, protection of building facades and public monuments from weathering however, results of this study indicate possibility of using the materials for wettability alteration of oil-wet carbonate rock in enhanced oil recovery (EOR) process.

In this study, gold nanoparticulate patterns were generated in polymer thick film using a direct light writing method and were characterized using optic, spectroscopic and transmission electron microscopy investigations. Based on physical and chemical process parameters that have an important contribution on the generated gold nanoparticle size, an artificial neural network was developed to predict the localized surface plasmon absorption maxima and consequently, the gold nanoparticles corresponding dimension. Due to the excellent predicting capabilities supported by a high correlation factor and low relative errors, the trial and error approach for generating the desired gold nanoparticle dimension is no longer used and, in addition, the samples are no longer destroyed for transmission electron microscopy measurements. Furthermore, correlations between the predicted gold nanoparticles dimension and the citrate to gold(III) ratio, scanning velocity and radiation intensity are investigated. The results highlighted that the absorption maxima along with its associated gold nanoparticles dimension increased with decreasing the intensity and the citrate to gold(III) ratio as well as with increasing the scanning velocity. The radiation intensity was found to have the most important influence on the gold nanoparticle size, followed by the scanning velocity and the citrate to gold(III) ratio.

Novel ZnO–MnO₂–Cu₂O (ZMC) triple nanocomposite (TNC) was synthesized via the facial synthesis method. For comparison, ZnO–MnO₂ (ZM) and ZnO–CuO (ZC) nanocomposites (NCs) were prepared. The prepared samples were characterized by UV–vis, FTIR, XRD, SEM, and EDS techniques. The optical activity of the samples was studied via UV–vis analysis. The FTIR spectra confirmed the presence of metal-O bands in samples. The crystalline structure of the samples was studied via XRD pattern. The morphology of the prepared compounds was analyzed via SEM images. The presence of Zn, Mn, and Cu in the prepared samples was confirmed via EDS test. The photocatalytic activity of ZM NC and ZMC TNC was examined by degradation of Rhodamine B and Direct Red dyes in visible light. In comparison, ZMC TNC degrades dyes considerably faster than ZM NC. The antimicrobial activity of ZMC TNC, ZM NC, and ZC NC displayed a high activity against the common pathogens Escherichia coli (E. coli, ATCC 9637) and Staphylococcus aureus (S. aureus, ATCC 12600) especially in the case of ZMC TNC. As an important achievement, the present researchers showed that the simple synthesis of TNCs is possible, and also TNCs have high capabilities due to their new, consolidated, triple and combined properties.

To expand the gallery of graphite functional materials, a graphite nanoplatelet fluid (GNF) is obtained via a three-step procedure, involving acid intercalant-assisted ultrasonic exfoliation, covalent grafting with a charged polysiloxane quaternary ammonium salt (DC5700), and ion exchange with a poly(ethylene) glycol-functionalized sulfonate salt (NPES). The obtained GNF exhibits flowability at room temperature exempted from any solvent. The 'two step' increase in thickness compared with its parent counterpart is attributed to the coverage of charged organic oligomer (DC5700/NPES bilayer) on the basal plane of GNP. The energy-dispersive x-ray (EDX) analysis of the intermediate and final products also demonstrate the existence of silicon (Si) in GNP-DC5700 and the appearance of sulfur (S) in GNF. Moreover, a relatively as high as ca. 78 wt% of organic fraction is calculated from thermal gravimetric analysis, which indicates 3.2 polymeric ion molecule per 100 carbon atoms. Typically, the digital photographs and zeta potential analysis of GNF aqueous solution demonstrates its good stability. Therefore, the polymeric ion bilayer and GNP are integrated into one single-component and macroscopically homogeneous, and thus can remain microscopically stable even under giant shearing force, making the novel GNF great potential as lubricants, plasticizers and functional nanofillers, etc.

This paper investigates the microstructural evolution and mechanical behavior of Al matrix especially the fatigue life when is reinforced with SiC nano particles. Al-SiC nanocomposite is fabricated using powder metallurgy (PM) methods. In this regards, suitable amounts of Al micro-particles and SiC nano-particles are milled using an attritor milling for 12 h. The milled powder is cold pressed under 400 MPa pressure and then is hot extruded with 8.5:1 extrusion ratio. This fabrication procedure gives nearly highly densified samples with less than 1% porosities. The main objective of this research paper is to study the effects of SiC nano reinforcement on variations of relative density, Vickers micro-hardness, compressive and tensile behaviors, and fatigue resistance of the consolidated nanocomposite specimens. The results presented an enhancement in micro-hardness, compressive and tensile strengths as well as a reduction in relative density of the material as the reinforcement content increases to 3 vol%. Further, fatigue life of the samples was improved after reinforcement by SiC nano particles.

A novel, simple, effective and rapid fluorescence sensing platform was fabricated using green silver nanoparticles from Agaricus Bispores (AgNP-AB).AgNP-AB was synthesized by microwave reactor. The synthesized AgNPs have been used for the fluorescence sensing of Hg(II) ions without the use of catalyst/modifiers or any other additional sophisticated instrumentation.The synthesized silver nanoparticles were fruitfully characterized by various analytical techniques. AgNP-AB leads to aggregation with Hg(II)ions in aqueous medium and leads to the formation of AgNP-AB-Hg(II) complex. The fabricated fluorescence sensing system for Hg(II) ions is related to the formation of AgNP-AB-Hg(II) complex. Concentration of Hg(II) ions was studied quantitatively from 0 to 90 μM via fluorescence sensing measurements. To the best of our knowledge, there are no reports for the fluorescence sensing of Hg(II) ion by green silver nanoparticles, and this novel technique could be adapted for effective fluorescence sensing platform for Hg(II) ions. We believe that our proposed approach would have multifunctional applications in various areas.

CoFe₂O₄ consisting of nanocrystallites were synthesized using glycine nitrate auto combustion, co-precipitation method and solid-state techniques. Both glycine nitrate auto combustion and co-precipitation method yielded nanosized CoFe₂O₄ (∼30–50 nm) particles whereas solid-state technique produced micron-sized (∼150 nm) cobalt ferrite particles. XRD and FTIR analysis confirmed the formation of the spinel CoFe₂O₄ structure. The frequency dependence of the dielectric constant for all the samples in the range 100 Hz–1 MHz, investigated in temperature regime of room temperature to 300 °C exhibited Maxwell-Wagner type interfacial polarization in consonance with Koop's phenomenological theory. Magnetic measurements were found to be strongly reliant on the particle size. Saturation magnetization decreased with decrease in particle size whereas the coercivity was found to increase from 1954 Oe to 2645 Oe as the particle size was reduced from 180 nm to about 24 nm. These deviations in the magnetic properties are ascribed to the grain size effects and cation redistribution, hence different synthesis techniques can lead to varied particle sizes and magnetic properties. Moreover, CoFe₂O₄ sample synthesized using sol-gel auto combustion technique find suitability in high frequency and magneto recording devices.

Application of drugs at local site is beneficial with less side effects. This study dealt with the development of nanofibers (NFs) based drug delivery system for local pain management in burn wounds with acetaminophen as model drug which has been proven to be an effective pain killer in mid to moderate burn wounds. The electrospinning process parameters were optimized by using Taguchi method. The optimized NFs were then selected for further characterization i.e. Fourier Transform Infra-Red Spectroscopy (FTIR), Scanning Electron Microscope (SEM), x-ray Diffraction (XRD) and Differential Scanning Calorimetry (DSC). The NFs final diameter varied from 185 to 375 nm. The optimized NFs showed good liquid absorption properties (∼11 g g⁻¹) with fast release of drug (∼80% in 60 min). The equilibrium drug release data was best followed by Ritger-Peppas kinetic model and showed case II transport mechanism. FTIR analysis confirmed that the drug was successfully incorporated within the NFs. DSC and XRD confirmed that the addition of drug increased the crystallinity of NFs but reduced the liquid absorption to some extent. The desired fast drug delivery along with good liquid absorption and moist environment of the fabricated NFs could be promising solution to manage pain in burn wounds at local site.

In this paper, the thermal and mechanical buckling of the nano flexoelectric beam with the Timoshenko beam model have been investigated by the consideration of nonlinear geometric effects. To do this, using non-classical theory of size dependent on flexoelectric materials, the coupling thermo-electromechanical and nonlinear equations are derived for the nano beam. The new formulation obtained here, is a modified strain gradient for flexoelectric materials, which is used in conjunction with the Timoshenko beam model to develop the governing equations for a flexoelectric beam. After obtaining the governing equations along with electrical and mechanical boundary conditions, the pre-buckling of the nano beam under mechanical and thermal loads was carried out and then the mechanical and thermal buckling of the nano beam was investigated. In the results section, the effects of different parameters on the behavior of the nano beam have been studied, and the results show that in the nanoscale, the flexoelectric effect greatly influences the piezoelectricity on this scale, and flexoelectric materials can be used as substitutes for the manufacture of various sensors and actuators.

This brief review paper discusses synthesis techniques for cerium (IV) oxide (ceria) that leads to relative differences in shape, size and dimension. The alterations in synthesis parameters have also been highlighted since it affects the desired application performance. For instance, the same synthesis technique of precipitation will result different morphology of ceria, once heat treatment is introduced. Furthermore, the synthesis technique complimentary with aging time generally will contribute to the better properties of the final product such as different ceria structure and thus resulting high surface area. Mostly the structure of ceria is precipitant dependent oriented. Therefore, the various selection of precipitant; sodium hydroxide, ammonia solution or oxalic acid will yield different structure, morphology and properties of ceria. Additionally, this paper reported on the recent applications in the catalysis, electrochemistry, and biomedical fields to justify the relevance and significant development of ceria.

We explore the ability of reduced graphene oxide (RGO) and titanium dioxide-decorated RGO (RGO-TiO₂) films to protect mild steel from corrosion in 3.5% NaCl. Graphene oxide (GO), prepared using a Modified Hummers method, was reduced using sodium borohydride. TiO₂ nanostructures were generated on RGO in a dispersion. The synthesized materials were characterized using UV-visible spectroscopy (UV–vis), Fourier Transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), Thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The obtained results confirm the exfoliation of graphite, reduction of graphene oxide, and formation of predominantly anatase phase of TiO₂, grown as nanotubes. Corrosion behaviour of mild steel, with coatings of GO, RGO and RGO-TiO₂, was studied using Tafel polarization studies and Electrochemical Impedance Spectroscopy (EIS). Tafel results showed that GO, RGO and RGO-TiO₂ shifted the corrosion potential anodically, indicating that they prevent the anodic dissolution of iron. A six order-of-magnitude reduction in the corrosion current was observed with GO-film-coated mild steel coupons, with further reduction resulting in the use of RGO and RGO-TiO₂ composite films. Impedance analysis showed that the films exhibited significantly enhanced charge transfer resistance for corrosion of mild steel by more than an order of magnitude compared to uncoated mild steel.

In this work a pure and well-crystallized kenyaite material was synthesized by hydrothermal method. It is then used to prepare silver-exchanged kenyaite materials active against pathogen bacteria strain by an ion exchange method. All the solids obtained were characterized by x-ray diffraction (DRX), Infrared FTIR spectroscopy, Scanning electron microscopy (SEM), Thermogravimetric (TGA), Energy-dispersive x-ray spectroscopy (EDX), diffuse reflectance ultraviolet (DRUV) analysis and x-ray photoelectron spectroscopy (XPS). Based on XRD results the structures of Kenyaite with different silver ratios are preserved after ion exchange. The XPS and DRUV analysis confirm that silver is loaded in both Ag⁺ and Ag° states. The SPR analysis indicate the presence of absorption band characteristics of silver nanoparticles (Ag-NPs) between 390 nm and 500 nm. Furthermore, the intensity of this band increases as the silver content in Kenyaite increases. Used as antibacterial agent against E. coli bacteria, the silver silver-exchanged Kenyaite materials display a relatively high antibacterial activity which is mainly due to the presence of Ag-NPs species located on the surface of the solid kenyaite matrix.

The eco-friendly synthesis of nanoparticles is an innovative step in the field of nanotechnology. Herein, we report a microwave assisted synthesis of silver nanoparticles using the leaf extract of a medicinal plant, Orthosiphon aristatus as both reducing and capping agent. Formation of orange colour with surface plasmon resonance peak at 436 nm in absorption spectrum confirms the formation of silver nanoparticles. Crystalline nature of the nanoparticles with face centred cubic geometry was confirmed from XRD and SAED patterns. TEM analysis showed that nanoparticles are spherical in shape and the size varies from 15–45 nm with average size 28.36 nm. The antimicrobial activities of synthesised nanoparticles were measured by agar well diffusion method against both bacterial and fungal strains. The bacterial strains used were Bacillus subtilis, Streptococcus sp, Enterobacter aerogenes and Pseudomonas sp. The fungal strains used were Penicillium citrinum and Aspergillus flavus. The nanoparticles show dose dependent increase in the zone of inhibition. DPPH assay was demonstrated that synthesised nanoparticles possess strong antioxidant activities. The catalytic activities of synthesised nanoparticles were examined by using them in the reduction reaction of nitro compounds like nitrophenol and nitroanilines with excess sodium borohydride. The nanoparticles show excellent catalytic activities and follow pseudo first order kinetics.

In this work, the silica/carbon nanocomposites are firstly fabricated by combining the cold-pressing methods and the sintering treatment, and then the thermal conductivity, the Seebeck coefficient and the electrical conductivity are experimentally studied. Results turn out that the thermal conductivity firstly decreases then rise with the increase of the sintering temperature, and there is an optimal sintering temperature for getting a low thermal conductivity. The decrease of the thermal conductivity is due to the enlarged porosity caused by a higher sintering temperature, while the rise arrives from the improved crystal degree of silica nanoparticles. Results also turn out that the Seebeck coefficient and the electrical conductivity of the silica/carbon nanocomposite are almost same to that of a common carbon material. This work is expected to supply some information for developing new thermoelectric nanocomposites.

Triethanolamine (TEA) was added along with acetic acid (AA) to enhance the stability of hydroxyapatite (HA) nanoparticles in isopropanol. H⁺TEA ions generated by AA and TEA reaction were adsorbed on particles and increased their zeta potential. Zeta potential increased to the maximum value at optimum concentration of AA (AA*) and then decreased with its further addition. Kinetics of EPD increased with AA addition into the TEA containing suspensions. Detachment of particles from deposits into the suspensions was the fastest at AA* due to the highest electrochemical potential difference at the interface. Sticking parameter (f factor) was the minimum at AA*. Corrosion rate of substrate considerably decreased in simulated body fluid (SBF) at 37 °C as the HA coating was applied on it. Apatite layer grew on the coating after its soaking in SBF at 37 °C for 1 week.

Phosphate-based phosphors have great potential in the application of white light conversion light emitting diodes (LEDs), but the highly hydrolysable speciality restricts its applications. In this work, an atomic layer deposition (ALD) vibrating fluidized bed is used to deposit alumina as a barrier layer of the phosphate-based phosphor powders. The surface morphology and conformality of coatings are characterized by scanning electron microscope (SEM) and transmission electron microscope (TEM), respectively. The barrier property is examined by pH measurement after immersing the sample into the deionized water. The influence of coating on luminescent properties is studied by the steady state/transient fluorescence spectrometer. It was observed that ALD Al₂O₃ can efficiently block the humid permeation and prevent the powders from the hydrolysis. Interestingly, the luminous properties are slightly improved after the powders are coated by Al₂O₃, i.e. a slight increase of PL intensity, a red-shift of the emission peak, except the fluorescence lifetime, which is slightly shortened.

In this work, SnO₂ nanoparticles are successfully fabricated by a simple hydrothermal route. The morphology and microstructure of the as-synthesized products are characterized by XRD, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. The results show that the as-obtained products possess tetragonal rutile structure. Photocatalytic activities of the as-synthesized products are studied by degradation of several kinds of organic dye molecules, revealing that eosin red solution is almost completely degraded after 18 min under ultraviolet light irradiation. Morphology dependent photodegradation experiments are also tested. The as-prepared SnO₂ nanoparticles possess still excellent photocatalytic activity after 5 times cycles, revealing their potential applications in eliminating organic contaminants in wastewater.

Gold nanoparticles demonstrate influential advantages when functionalized with bio-molecules. The Pectin/Gold Nano Colloidal Dispersion (P/G NCD) and folic acid-Pectin/Gold Nano Colloidal Dispersion (FA-P/G NCD) were synthesized by simple chemical reduction method to obtain monodispersed functionalized gold nanoparticles and were characterized. The influence of promoting excited oxygen molecule in curcumin was studied, with and without Ultraviolet light (UV) irradiation using green reagent. The formation of folic acid-pectin (FA-P) conjugates affects the capping of gold nanoparticles when compared to pure pectin, this was confirmed using Fourier transform infrared spectra (FT-IR), Ultraviolet Visible spectroscopy (UV–vis), Transmission Electron Microscopy (TEM), Dynamic light Scattering (DLS) and zeta measurements. The FA-P conjugates irregularly tethers on to the nanoparticle surface leaving randomly extended flagellate regions over the surface of gold nanoparticles. Surface Plasmon Resonance (SPR) of gold and folic acid enhanced the effect of curcumin production of singlet oxygen generation in P/G NCD and FA-P/G NCD, which will promising for effective theranostic applications.

Ag/AgCl-modified TiO₂ nanotube photocatalysts (noted as Ag/AgCl/TiO₂ nanotubes) are synthesized by the combine of deposition-precipitation and photoreduction methods firstly, and then reduced graphene oxide (rGO) is deposited on the Ag/AgCl/TiO₂ nanotubes via a simple one-pot solvothermal method. TEM, HRTEM, XRD and UV–vis are utilized to characterize the morphology, microstructure, composition and optical property of the obtained samples. The photoactivities of samples are evaluated by the photodegradation of methyl orange under ultraviolet and visible light irradiation, respectively. The effects of contents of AgCl, Ag and rGO on the photocatalytic performance of Ag/AgCl/TiO₂ nanotubes and rGO modified Ag/AgCl/TiO₂ nanotubes are investigated, respectively, and their optimal contents are obtained. The results reveal that, after Ag/AgCl modification, the samples exhibit an absorption in visible region due to the surface plasmon resonance of metallic Ag nanoparticles. Besides that, the enhanced photocatalytic activities of Ag/AgCl/TiO₂ nanotubes and rGO modified Ag/AgCl/TiO₂ nanotubes samples are observed during ultraviolet and visible light irradiation. Based on the results, the different photocatalytic mechanisms under ultraviolet and visible light irradiation are proposed.

Electrospun nanofibres were prepared starting from a dispersion of Nickel magnetic nanoparticles (MNPs) in Polydimethylsiloxane (PDMS) and Tetrahydrofurane (THF). Coaxial electrospinning was used to realize a temporary structure which wraps PDMS fibers into a thin shell of PolyvynilPirollidone (PVP), in which the crosslinking reaction of the inner fiber core is completed. After the removal of the PVP shell, the fiber skeins exhibit remarkable elastomagnetic deflection induced by transversal magnetization. The proposed methodology could potentially open up really intriguing perspectives in the fabrication of devices—deformable by magnetic forces—for bio-electronics and bio-medical applications.

Invisible Ag-grid transparent electrodes with a variety of spacing between the Ag-grid lines of 100, 150, 200, 300, 500 and 1000 μm at a constant line width of the Ag-grid of 5 μm and a constant thickness of the Ag-grid of 0.6 μm have been prepared by a conventional gravure offset printing using our newly developed Ag nanoparticle ink. In optimizing the Ag-grid electrodes, the transmittance is up to 98% in the visible light region and the sheet resistance is down to 3 Ω/□. Moreover, the Ag-grid electrodes have been laminated with a poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) layer. In the Ag-grid laminated with PEDOT:PSS electrodes, the transmittance is up to 96% in the visible light region and the sheet resistance is down to 4 Ω/□. The Ag-grid laminated with PEDOT:PSS electrodes would have potential applications as flexible and transparent conductive films in optoelectronics and photovoltaics.

A low-cost heterostructure of a wide-bandgap nanostructured semiconductor on top of a transparent conductor (TC) fabricated from abundant sustainable materials is of great interest for optoelectronic devices, such as heterojunction photovoltaic cells. Due to its high optical transparency and electron mobility, graphene is an attractive carbon-based material to replace the costly traditional TCs (i.e. ITO), which pose health hazards and destructive environmental impact thorough their life cycle. However, for the industrial application of graphene as TC it is necessary to interface it with other materials, like oxides, while maintaining the sp² network that provides its excellent electronic properties. We report the optimized electrodeposition of ZnO on graphene to obtain a textured layer of vertically aligned crystalline semiconducting nanorods (ZVNRs) evenly coating the graphene surface. Lattice distortions and mosaicity in the crystals indicate that the ZVNRs grow under out-of-plane compressive strain. The stability of the sp² network of graphene during in situ growth of ZnO is demonstrated using Raman spectroscopy from the front and backside of the heterostructure, in a novel approach to investigate junctions of 2D–3D nanomaterials. Despite the structural stability of graphene, its R_□ is found to increase by ∼100% with ZVNRs electrodeposition, which is attributed to reduction of mobility due to charge carrier scattering, reduction of carrier concentration due to doping, and/or interfacial strain. The cathodic electrodeposition is demonstrated to be an effective and versatile method to grow crystalline nanostructures in the surface of single layer-graphene while protecting its sp² hybridization, and it provides relative fast deposition rates, affordability, and low processing temperatures that would allow using polymeric flexible substrates and. These findings on interfacial properties are important to advance the functionality of graphene as TC material and develop nano-heterostructures for myriad technological applications.

Kenaf is a plant which grows fast and has good environment adaptability. It is one of the most traditional natural cellulosic fiber plants in the word. However, the high lignin content and small fiber size block its application on textile fiber production and bioenergy refinery. Nanocellulose turns out a promising way to take advantage of the kenaf resource. Herein, combined microwave and chemical treatment was employed to extract nanocellulose from kenaf bast directly. The fiber size and chemical components during the extraction processes were analyzed. Then the kenaf nanocellulose is characterized by transmission electron microscopy, x-ray diffraction and thermogravimetric analysis. The results suggest that: most of the non-cellulosic materials such as lignin and hemicellulose was removed from kenaf bast after microwave and bleaching progress, producing micron size fibers; the kenaf nanocellulose extracted by the combined microwave and chemical treatment showed an acicular morphology with nano-size fiber; it has a higher cristallinity but a bit lower thermal stability compared with raw kenaf bast. In a word, this combined treatment is significantly effectual for preparing kenaf nanocellulose. It is expected that the results can serve theoretical basis for subsequent utilization of kenaf nanocellulose.

The viscoelastic properties of carbon nanotube (CNT) reinforced epoxy resin were researched experimentally, in this study. To this end, single walled CNT with CY 219 epoxy resin and HY 5161 hardener were utilized and dynamic mechanical thermal analysis (DMTA) and creep tests were carried out. The DMTA were performed in several frequencies and the effects of the CNT weight percent and the frequency of the test on the storage and loss moduli were investigated. Additionally, frequency-sweep DMTA at room temperature were carried out to obtain master curve of the mentioned moduli in terms of the frequency. To evaluate viscoelastic properties of the composite in time domain, creep tests at room temperature were conducted. The effect of CNT content on the time dependent results were studied. A combination of molecular structural mechanics and micromechanics modeling was implemented to predict overall viscoelastic properties in time and frequency domains. The effect of CNT length and agglomeration were taken into account in the modeling. Comparison between model prediction and experimental results shows good agreement when the short agglomerated CNTs were considered in the model.

Anatase phase nano TiO₂ (NT) with the diameter of 10 nm and 15 nm were used to modify cement-based composites. The results demonstrated that NT can enhance the compressive strength of cement-based composites cured at 28 day by 18.50%/18.42 MPa and 6.41%/6.38 MPa, respectively. Both two sizes of NT can increase the polymerization degree and the average silicate chain length of [SiO₄]⁴⁻ in C–S–H. Moreover, they can decrease the CH orientations, restrict the CH size and endow the cement-based composites with more compact microstructure. Hence, the flexural strengths and the flexural strength to compressive strength ratios of cement-based composites cured at 3 day and 28 day have been significantly increased. Based on the nucleation free energy theory, the number of nucleating points of 10 nm NT is more than that of 15 nm NT, and the energy needed to be nucleated for each nucleating point of 10 nm is less than that of 15 nm NT. Therefore, the nucleation effect caused by 10 nm is greater than that caused by 15 nm NT and the enhancement effect of 10 nm NT on the mechanical property of cement-based composites was better than that of 15 nm NT at the same content and curing age.

A multilayer graphene paste electrode (MGPE), consisting of graphene flakes and mineral oil, was modified with activated carbon (AC). The AC was produced from coconut husk using zinc chloride as the activating agent. The AC/MGPE was fabricated by substituting an amount of the multilayer graphene (MG) with the AC, and the resulting paste was packed in a Teflon syringe. The electrode was used to simultaneously detect lead (Pb²⁺) and cadmium (Cd²⁺) via anodic stripping voltammetry (ASV). The amounts of MG and AC in the electrodes were varied by substituting the amount of the former with the latter (by percent) and the best electrode was found to consist of 5% AC and 95% MG. The optimal parameters, accumulation time, deposition time, and deposition potential were determined. The optimized parameters were used on the said best electrode to determine the calibration curve and limit of detection. The peak current had a linear relation with the concentration of the heavy metals with a correlation value (R²) of 0.9956 and 0.9973 for Cd²⁺ and Pb²⁺, respectively. After which the electrode was used to detect heavy metals in vegetable samples, and the results were verified via atomic absorption spectroscopy. The heavy metal concentrations that were detected in most of the samples were above the maximum limit as dictated by the World Health Organization.

Microglobules of polyaniline (PANi) synthesized by chemical bath method on commercial steel plates that have been used as the catalyst support for tungsten trioxide (WO₃) particles fabricated by hydrothermal method. The crystalline phases and surface analysis of the WO₃, PANi and WO₃/PANi film were examined using x-ray diffraction and scanning electron microscopy, while electrochemical capacitive properties were determined using cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and galvanostatic charge-discharge (GCD). The PANi incorporated WO₃ film influences significant catalytic performance wherein a pseudo-capacitor was obtained. The constant phase element was considerably eliminated in WO₃/PANi hybrid film. The cyclic stability was scrutinized via GCD technique. The degradation of specific capacitance observed low (2.61%) after 3000 GCD cycles, indicating superior cycling stability of WO₃/PANi supercapacitor.

A new interesting third-order nonlinear (NLO) organic material Pyrrolidinium 3-nitrophthalate (PY3N) is synthesized by water solvent in an equimolar ratio by room temperature solution growth technique. The crystal system (monoclinic), space group (P2₁/c and lattice constants (a = 13.245 (9) Å, b = 11.775 (7) Å, c = 8.612 (5) Å, β = 99.265 (2)°) were obtained from single crystal XRD. The vibrational and NMR spectral analyses confirmed the different functional groups and chemical environment of molecules present in the crystal lattice. The UV–vis study showed the crystal has good transparency with band gap and the index of refraction displays the normal dispersion behavior. The crystal demonstrates moderate surface tolerance to laser power (4.887 GW cm⁻²). The non-linear parameters were estimated by Z-scan technique. We have investigated the second order hyperpolarizability 'γ' of PY3N crystal with electric field and frequency by using HF method with 6-311++g(d, p) level. The theoretical third order susceptibility χ⁽³⁾ value is 0.196 × 10⁻⁶ esu. The experimental χ⁽³⁾value is 3.131 × 10^–6 esu. The effective optical limiting action is directed by PY3N crystal. The crystal is identified as a soft material from hardness measurement. The PY3N crystal has thermal stability (189 °C) which is identified using thermal analysis. The thermal activation energy (77.286 kJ mol⁻¹) is determined from TGA data. The good quality of the crystal is confirmed from the intense photoluminescence peak. The etching study revealed the elongated square pattern on the developed crystal surface.

Glass bonding is often necessary in microfluidic, nanofluidic and MEMS applications. Fusion bonding is a popular method in which glass substrates are permanently bonded using chemical treatment, low pressure and annealing. This project investigates a range of bonding methods and measures the bond strength. Float glass substrates were chemically cleaned and prepared using four different methods (Ethanol Rub, Ethanol Rub + NH₄OH, piranha + NH₄OH, and piranha + HCl + NH₄OH), pressed together by hand, and placed in the oven at 400 °C for 10 h. Bond strength was assessed using compressive shear stress. It was determined that the piranha + HCl +NH4OH produced the strongest bond. All methods produced satisfactory bonds and the simplicity and safety of a simple Ethanol rub means it should be considered whenever possible.

We report red and green upconversion luminescence in high-silica luminous glass under irradiation by an infrared femtosecond laser. The luminous glasses were fabricated from sintered porous glass impregnated with the rare earth ion Eu³⁺ or Tb³⁺. The luminescent spectra under femtosecond laser excitation reveal that the red and green upconversion luminescence results mainly from the transitions ⁵D₀ → ⁷F₂ in Eu³⁺ and ⁵D₄ → ⁷F₅ in Tb³⁺. The dependence of the fluorescence intensity on the pump power indicates that the conversion of infrared radiation to visible emission is dominated by two- and three-photon excitation processes, respectively. It is suggested that the upconversion mechanism is simultaneous absorption of two or three infrared photons, which shifts the Eu³⁺ and Tb³⁺ ions to their excited states; they quickly cascade down to the lowest excited states. Thereafter, the Eu³⁺ and Tb³⁺ ions relax radiatively to their ground states, creating bright red and green fluorescence.

Stick-slip (SS) is a mechanical instability which occurs on sliding interfaces in low velocity regimes in form of jerky motions. In this article, SS behaviour of gelatine hydrogels sliding on a smooth glass substrate is investigated in direct shear experiment using fracture mechanics. It is observed that average value of shear stress amplitudes and corresponding energy release rate (ERR) decrease with increase in pulling velocity upto the critical velocity. Time of relaxation is also found to be sliding rate dependent in the experiment. The video analysis of interfacial crack propagation reveals that crack length increases to a critical value and becomes unstable at the last phase of 'stick' period, but the same crack begins to restore to its original length just after 'slip' phase. The hysteresis present during the stick-slip motion diminishes at the critical velocity. Finally, this present study establishes that stick-slip is basically governed by the competition between rate dependent crack growth and crack healing along the sliding interface.

The abrasive wear behavior of Epoxy strengthened Hallosyite nanotube (HNT)/Nano silica (separated from bamboo leaves) composite were tentatively examined utilizing pin on disc test rig. Multiple linear regression equations have been utilized to discover the impact of different factors which influences the abrasive wear behavior of composites. Analysis of variance has been locked in to get indiudival interaction impact of each process parameters (percentage of reinforcement, normal applied load and sliding speed) which influences the abrasive wear of the hybrid composite. Results demonstrate that the dry sliding wear of epoxy strengthened HNT/nano silica composite declines with increment of the reinforcement content. The load conveying limit of the epoxy in dry sliding condition has been expanded with the nearness of HNT and nano silica. Micro-structural examination was completed to research the different wear mechanism of the hybrid polymer composites utilizing scanning electron microscope (SEM).

A novel spectrum-fingerprint anti-counterfeiting fiber was developed by using Sr₂ZnSi₂O₇:Eu²⁺,Dy³⁺ and polyacrylonitrile (PAN) as main raw materials by wet spinning. The microstructure, phase structure and spectral properties of the fiber were studied by SEM, XRD and Fluorescence spectrophotometer. The results show that the Sr₂ZnSi₂O₇:Eu²⁺,Dy³⁺/PAN spectrum-fingerprint anti-counterfeiting fiber has similar luminescence characteristics to those of Sr₂ZnSi₂O₇:Eu²⁺,Dy³⁺, the excitation wavelength of which is near 360 nm and the strongest emission peak is 470 nm. Although the addition amounts of luminescent material had no effect on the luminous wavelength of the fiber obviously, it had a great influence on the luminescence intensity of the fiber. Sr₂ZnSi₂O₇:Eu²⁺,Dy³⁺/PAN composite fiber keeps the basic characteristics of spectrum-fingerprint anti-counterfeiting fiber and is a new potential anti-counterfeiting fiber with higher anti-counterfeiting force.

The blending of immiscible polymers and their compatibilization leads to materials with tailor-made properties suitable for wide range of applications. Polypropylene (PP) and polylactic acid (PLA) were blended in different weight ratios and the optimized blend was compatibilized with maleic anhydride grafted PP (MA-g-PP) in varying amounts from 0 to 5 wt%. Rheological studies performed using a capillary rheometer showed the pseudo plastic behavior of the blends and from the shear viscosity data, it was observed that 3 wt% of the compatibilizer effectively compatibilized the selected blend. Mechanical properties further confirmed this finding. Thermogravimetric analysis revealed a two-stage degradation mechanism for the blends, corresponding to each component in the blend system. The apparent activation energy (E_a) values for the thermal degradation were calculated using Kissinger method, Horowitz and Metzger method, Kissinger–Akahira–Sunose equation, Friedman model and Ozawa–Flynn and Wall method. Coats-Redfern method was used to elucidate the mechanism of thermal degradation of the chosen blend system. The E_a values for PLA component of the blend increased with increase in compatibilizer addition up to 3 wt% and then decreased, whereas, it decreased for PP fraction up to a compatibilizer level of 3 wt% and then increased.

Compatibilized and uncompatibilized immiscible blends of polystyrene and low density polyethylene at various blending ratios were prepared by melt mixing using an internal batch mixer. Two kinds of similar structure tri-block copolymers as compatibilizers were employed: styrene-butadiene butylene-styrene (SBBS) with long blocks of polystyrene, and styrene-ethylene butylene-styrene (SEBS) with long blocks of poly(ethylene-butylene). The influence of the compatibilizers on morphology, thermal and mechanical properties of different blends were analyzed and compared by using scanning electron microscope (SEM), differential scanning calorimetry (DSC), x-ray diffraction (XRD), impact and tensile tests. Also, linear dynamic rheological properties of different blends were analyzed and interfacial tensions between the blend components were calculated by using Palierne model. The Cole-Cole plots were established to bring more insights into the results of viscoelastic measurements. Significant difference appeared in thermal and mechanical properties between the compatibilized blends using SEBS and SBBS. It was found that type and length of blocks in the compatibilizers along with the ratio of the blends controlled the interfacial tension, droplet size and the mechanical properties of the given blends.

In order to improve the mechanical and heat resistant properties of epoxy acrylate (EA), modified talc powder (mTAP) was added into EA. In this work, talc powder (TAP) was modified with 3-(trimethoxysilyl)propyl methacrylate (MPS). Fourier transform infrared spectroscopy (FTIR), x-ray diffraction (XRD), and Malvern laser particle size meter (PSA) were used to characterize the effect of modification. Results showed that MPS was grafted on TAP surface. Then the modified talc powder (mTAP) was uniformly dispersed in blend resin. Specimens were made by a stereolithography apparatus (SLA) 3D-printer. The tensile strength, elongation at break, impact strength and volume shrinkage of specimens were investigated. Optical microscopy, scanning electron microscopy and thermogravimetric analyzer were used to study the dispersion state of mTAP, microstructure and heat resistance of the specimens. By analyses, it was revealed that the addition of 5 wt% mTAP had the best effect. Studies showed that addition of mTAP could effectively reduce the volume shrinkage and improve the mechanical properties of specimens.

Corrosion is one of the biggest problems faced by the society in the present world. It causes economical loss as well as degrades the service life of the materials. In present study we demonstrate synthesis and characterization of corrosion resistant coating Poly (o-phenitidine)/SiO₂/Epoxy. The polymer composite was synthesized by chemical oxidative polymerization of o-phenitidine and silica nanoparticles. The composite coating was synthesized using FTIR and XRD. The morphological analysis was carried out by Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). All Electrochemical Studies was carried out in saline condition (3.5 wt% NaCl). The Electrochemical Impedance Spectroscopy (EIS) and Tafel analysis results demonstrate good inhibition properties of coatings. The salt spray test results show no extension of corrosion around Cut Mark Scribed on epoxy coatings loaded with Poly (o-phenitidine)/SiO₂ composites. The results demonstrate the synergistic combination of polymer and nano filler material that causes improvement in corrosion resistant properties.

Dielectric polyvinylidene fluoride (PVDF) and Barium titanate (BaTiO₃)-PVDF nano-fibrous composites were made using the electrospinning process based on a design of experiments approach. An ultrasonication process was optimized using 2^kfactorial DoE approach to disperse BaTiO₃ particles in PVDF solution in DMF. Scanning electron microscopy was used to characterize the microstructure of the fabricated mesh. The FT-IR and Raman analysis were carried out to investigate the crystal structure of the prepared mesh. Surface morphology contribution to the adhesive property of the composite was explained through contact angle measurements. The capacitance of the prepared PVDF-BaTiO₃ nanofibrous mesh was a more than 40% increase over the pure PVDF nanofibers. The results obtained indicates that electrospinning offers a potential way to produce nanofibers with desired crystalline nature which was not observed in molded samples. In addition, BaTiO₃ can be used to increase the capacitance, desired surface characteristics of the PVDF nanofibers which can find potential application as flexible piezoelectric sensor mimicking biological skin for use in structural health monitoring applications.

A paradigm shift from petrochemical based packaging films for food packaging due to its non-renewable and waste disposal challenges has motivated research interest in development and characterization of biopolymer films. In this study, biocomposite films was prepared using bamboo fiber to reinforce modified and unmodified red seaweed SW Kappaphycus alvarezii, resulting in improved mechanical characteristics of 109.1 MPa tensile strength, 55.4 MPa Young's Modulus and 22.3% stretchability prior to breakage at the optimum value of 15% bamboo fibers loadings for unmodified biocomposite. There was general improvement in the fiber/matrix interface of the modified SW based composite films over the biopolymer films from unmodified SW bamboo reinforced films resulting in improved water vapour barrier as the fiber load increases up to Water vapour permeability value of 5.2 (g/s/m²/Pa)., while the contact angle as high as 91° was obtained. FTIR analysis validates the effective interaction of both the bamboo fibers and the seaweed matrix without any significant biochemical alteration of the seaweed within the frameworks of composite films. SEM characterization and contact angle measurement indicate that heterogeneous surface modification of the biopolymer film increases with the fiber loading. Results demonstrated the potential use of the renewable and biodegradable biopolymer composite films as packaging films useful in the food industry.

Silicone elastomers (poly dimethyl siloxane, PDMS) are widely used in the fabrication of MEMS devices and in mechanobiological studies. Mechanical properties of the elastomers may be varied by changing the crosslinking density and physical entanglements in the networks. Other factors like dangling chains and uncrosslinked sol fractions also influence the network mechanics. We investigated the role of crosslinks, entanglements and sol fraction in the mechanical properties of PDMS prepared with different ratios of base to crosslinker. Results from compression tests show greater elastic modulus for the highly crosslinked networks. We removed uncrosslinked sol, altered the entanglement density with xylene extraction, and used data from mechanical tests to assess predictions from the Frenkel-Flory-Rehner model. These studies show that the polymer-solvent interaction parameter, χ, varied linearly with the equilibrium volume fraction. Dynamic mechanical analyses of extracted PDMS samples showed that crosslinking density, solvent presence, and sol fraction affect their overall viscoelasticity properties. We also compared experimental data with scaling laws and demonstrate that trapped entanglements in the networks contribute to the mechanical properties of PDMS. Finally, we show from these studies that swelling behaviors of PDMS in xylene follow affine deformation.

To study the effect of dopant type and dopant concentration on the properties of Polyaniline, a transition metal acid and an organic sulphonic acid were selected. Polyaniline with three different dopant concentrations (0.01 M, 0.05 M and 0.1 M) of each acid were prepared by chemical oxidative polymerisation using Ammonium persulphate as oxidant at 0 °C–5 °C. The morphology of the samples obtained was characterized by Field Emission Scanning Electron Microscopy (FESEM), structures were analyzed using Fourier Transform Infrared Spectroscopy (FTIR), optical properties by UV-visible spectroscopy and Photoluminescence spectroscopy. Dielectric property measurements reveal that organic sulphonic acid doped polyaniline exhibited high value of conductivity and dielectric constant than transition metal acid doped polyaniline. The samples with higher values of conductivity were selected for photocatalytic degradation study of Methylene blue under visible light irradiation. The higher degradation rate of 70.59% obtained from photocatalytic activity measurements reveals that organic sulphonic acid doped polyaniline is a better photocatalyst than transition metal acid doped one.

In this study, we have synthesized poly-methyl methacrylate (PMMA) and its silica doped composites. The PMMA-silica composites were synthesized using in situ polymerization. The synthesized composites were characterised and the results were compared with the data available in the literature based on various synthesis route. In our study, we noticed increasing trend in specific gravity and hydrophobicity with the increase of silica concentration in PMMA-silica composites. However, refractive index, band gap and interaction between different PMMA chains showed decreasing trend with the increase of silica concentration in the composites. SEM images revealed the increase of surface roughness with the increase of silica concentration. We have noticed contradicting trend in refractive index and surface morphology results as discussed by O G Abdullah et al and H Wang et al respectively. However, contact angle results and Tauc plot were in accordance with the results obtained by P N Manoudis et al and O G Abdullah et al respectively.

The silk fabric was modified with 4-nonafluorobutyl-4'-azobenzol acrylate (NFBA) through atom transfer radical polymerization (ATRP). FT-IR and XPS were used to confirm the structures of the silk fabric before and after modification. The surface morphology was recorded by SEM and surface property was tested by contact angle (CA). The reversible isomerization of azobenzene on silk was observed by processing with UV and visible alternately. As a result, the reversible hydrophobicity-hydrophilicity transformation on silk fabric was successfully achieved by controlled grafting polymerization via ATRP.

A novel environmental friendly plasticized PLA kenaf biocomposites were fabricated by melt blending technique through a combination of epoxidized jatropha oil, one such non-edible vegetable oil material and renewable plasticiser. The mechanical and morphological properties of the composites were evaluated. The addition of EJO with 40% kenaf treated fibre on PLA had improved the mechanical properties of the polymer composites. SEM micrographs clearly revealed the good physical interlocking for PLA and kenaf fibre for 40% kenaf treated fibre while untreated kenaf contributed to poor filler-matrix compatibility attributes that leads to filler-related failures which resulted voids. Alkalisation of kenaf fibre provides good interaction bonding between kenaf and PLA matrix which resulted on increased of value of mechanical properties of treated biocomposites compared with the untreated biocomposites.

Coal fly ash (CFA) was utilized as a raw material for the synthesis of zeolite X. Zeolite of X-type was synthesised from CFA through alkali fusion tailed by hydrothermal treatment. The main crystal-like stage of fly ash, quartz could be also converted to pure X-type through hydrothermal suitable treatment using SiO₂/Al₂O₃ components of the amorphous stage in coal fly ash along with the gel composition of 14.76 Na₂O: 1 Al₂O₃: 3.5 SiO₂: 454 H₂O. The properties of zeolite X formed strongly depends on the treatment circumstances and concentrations of raw materials. The synthesised zeolite X from CFA was characterized by XRD, SEM-EDS, HR-TEM, SAED and FTIR which represents the appearance of crystalline quartz and mullite with spherical/hexagonal morphology. The predominant morphology was spherical particle with diameters ranging between 23.80 nm to 190.5 nm. By rising the SiO₂/Al₂O₃ ratio of preliminary material, degree of crystallinity also increased maximum at SiO₂/Al₂O₃ is 1.7. The cytotoxic influence of zeolite X on cancer cell lines like HEP2, HT-29, HEPG2 and A549 were evaluated. General outcomes exhibited that cancer cell lines treated with 200 μg ml⁻¹ of zeolite X showed the greatest inhibition of cell proliferation and reduction in cell viability. These findings provides preliminary information to determine the prospective utilization of zeolite X as anticancer agent for alternate or complementary therapy.

A common assumption of nanoidentation experiments is to consider the sample as an elastic half space due to the simplicity of the analysis regarding the Young's modulus calculation. However, in the nano—dimensions a sample cannot be considered as a half space and this approximation can lead to significant errors in the analysis. In this paper, the Atomic Force Microscopy (AFM) nanoindentation method on cylindrical and spherical shaped samples is discussed. The purpose of this paper is to investigate the errors that arise under the assumption that a cylindrical/spherical shaped sample is a half space and to provide a simplified methodology to reduce these errors. The new approach can be applied to AFM nanoindentation experiments on cylindrical or spherical biological samples (e.g. collagen fibers and cells).

The present study was aimed to synthesis copper oxide nanoparticles by green chemistry method. Copper oxide nanoparticles (CuO–NPs) were synthesized using Solanum lycopersicum aqueous leaf extract. The synthesized CuO–NPs were characterized by UV–visible spectroscopy, Field emission-scanning electron microscopy (FE-SEM), High resolution-transmission electron microscopy (HR-TEM), Energy dispersive x-ray spectrometer (EDX), and Dynamic light scattering spectrometer (DLS). FE-SEM and TEM observation showed that the average size of 20–40 nm with spherical shape of CuO–NPs and the presence of phytochemicals which are responsible for reduction and stabilization were studied by FT-IR. XRD studies revealed the monocyclic crystalline phase of CuO–NPs. The synthesized CuO–NPs showed significant antibacterial activity against both Gram positive and Gram negative bacterial pathogens, assayed using agar well diffusion method and synthesized CuO–NPs induce significant morphological changes to bacterial pathogens, determined using FE-SEM. Furthermore, photocatalytic degradation of crystal violet (CV) under visible light irradiation using CuO–NPs was performed. Synthesized nanoparticles exhibited 97% degradation activity for CV. Overall our studies supported the eco-friendly, green synthesized CuO–NPs can be used as potential biocidal and photocatalytic agents.

In the joint chemical reduction of silver and copper ions in the presence of gelatin, regardless of the composition of the reaction medium, a nanocomposite was formed consisting of nanodispersed silver and copper particles. In this research, the dependence of phase composition and dispersity on the synthesis conditions, as well as antibacterial activity of synthesized silver and copper nanocomposites were studied. It has been established that the most highly dispersed silver and copper nanocomposites were formed in an alkaline medium. We have revealed that nanocomposites of Ag-Cu system which were synthesized in an alkaline medium possessed significant antibacterial activity against the Erwinia amylovora and Pseudomonas syringae bacteria.

Herein we report, a simple strategy for the synthesis of hexagonal wurtzite ZnO and Nd doped ZnO (Nd/ZnO) using sonochemically assisted chemical co-precipitation method. The samples were characterized by standard analytical techniques, such as Fourier transform infrared and UV–vis spectroscopy (FTIR), x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy dispersive x-ray (EDX) analysis, Photoluminescence (PL) and specific surface area analysis (BET). The XRD results showed that the synthesized ZnO and Nd/ZnO samples were crystalline and accumulated as interleaving polyscales with flower like structure. A redshift is observed in Nd/ZnO samples in comparison with ZnO with increased visible light absorption ability. The band gap energy of Nd doped samples is observed to decrease from 3.21 for pristine ZnO to 3.17 eV with an increase in Nd content. The photocatalytic studies over Rhodamine 6G revealed that the Nd/ZnO samples exhibited excellent photocatalytic activity compared to pristine ZnO. 5% Nd/ZnO showed highest (97.39%) photocatalytic performance for dye removal which is attributable to high surface area 23.949 m² g⁻¹ together with the efficient increase in the rate of separation of photogenerated electron-hole pairs and capability of hydroxyl radical's generation as evidenced by UV–Vis absorbance spectra.

Vanadium monoxide (VO) nanoparticles and reduced graphene oxide (rGO) composites with a 3D architecture (GVO) was synthetized by a simple hydrothermal reaction of a mixture of vanadium pentoxide (V₂O₅) ribbons and graphene oxide (GO). It shows large contact area between electrode and electrolyte, short electron and ion diffusion pathways for LIBs and good electrical conduction. As a result, when the GVO was served as the LIBs anode material, the resulting electrodes exhibited a high specific capacity (909 mAh g⁻¹ at 74.4 mA g⁻¹ after 30 cycles) and remarkable cyclic stability.

In this article, synthesis of ZnO nanoparticles and the formation of a nanocomposite with activated charcoal (AC) as an electrode material for supercapacitor applications are discussed. The nanoparticles of size approximately 25.5 nm are prepared at room temperature by a co-precipitation method. The calcination temperature for the phase formation is observed to be 600 °C. The supercapacitor fabricated with the synthesised nanocomposite (ZnO–AC) and 1 M Na₂SO₄ as an electrolyte results into the specific capacitance of 106.1 mF cm⁻². The equivalent single electrode specific capacitance for the same supercapacitor is about 68.2 F g⁻¹. Materials are characterized with the help of synchrotron x-ray diffraction (SXRD), scanning electron microscopy (SEM) and electrochemical characterization. The study proposes the use of nanocomposite (ZnO–AC) as an electrode material for energy storage devices such as supercapacitor.

The removal of toxic heavy metals (Cd, Pb and Hg) from aqueous solution has been attempted in two different modes by using macromolecular assisted and immobilized multilayered modified polyether sulfone membranes (PES). PES membrane was modified with chitosan (CHI) and poly (styrene sulfonate) (PSS) using layer by layer (LbL) method. Humic acid (HA) and cholesterol (CHO) were used for immobilization. SEM and AFM confirmed that the obtained films were rough and highly porous. FTIR analysis confirmed successful immobilization of macromolecules in poly-ion coated membranes. Ellipsometric studies confirmed that the thickness of system increased with immobilization. Thermogravimetric analysis proved that the membranes were thermally stable upto 550 °C. The macromolecule assisted low pressure filtration was carried out by the addition of HA and CHO to the respective spiked metal ion solutions prior to filtration. More than 98% of the heavy metal ions were retained by macromolecules immobilized membranes. For Cd²⁺ ions, rejection efficiency of 6 bilayered PES membrane achieved ∼90% with HA and CHO immobilized at a concentration of 20 μmol/L and 400 μmol/L respectively. For Pb²⁺ ions, rejection efficiency attained ∼90% for HA (2 bilayered system) and for CHO (4 bilayered system) immobilized at 15 μmol/L and 400 μmol/L respectively. The rejection efficiency for Hg²⁺ ions obtained above 95% for both HA and CHO immobilized membranes at 2 bilayer with concentrations 15 μmol/L and 300 μmol/L respectively. The macromolecule assisted filtration also showed very good removal for all metal ions with efficiency above ∼90%. High macromolecule concentration with high number of bilayers has resulted high flux with negligible effect on the retention of heavy metals. Thus, this membrane system provides a very simple, efficient, easy and convenient approach for the removal of toxic metal ions by employing a combination of poly-ion coated polymer membrane with macromolecules.

This paper analyses the tribological properties of commercialised palm base oil blended with zinc dioctyldithophospate (ZnDoDP) as a substitute for mineral-based oil, which, despite its known drawbacks, is commonly used in the lubricant industry (automatic transmission fluid). Palm oil was mixed with ZnDoDP as an additive at a range of concentrations from 0 to 3.0 wt%. The samples were mixed using an ultrasonic homogeniser. Then, the samples were tested to determine their lubricant properties via elemental analysis as per ASTM D6595, viscosity index (VI) as per ASTM D2270, and total acid number (TAN) as per ASTM D664. A tribological test was then performed using a four-ball tester as per ASTM D4172, with the worn surfaces of the balls imaged using Scanning Electron Microscopy (SEM) and Energy-dispersive x-ray Spectroscopy (EDX). The results found that 2.0 wt% of ZnDoDP shows excellent characteristics in terms of its lubricant properties, coefficient of friction, and wear. However, ZnDoDP mixed with palm oil reported a higher acid number due to the acidic characteristic of the additive itself.

Titanium dioxide (TiO₂) is a widely used electron transport material in organic-inorganic hybrid perovskite solar cells (PSCs). In order to reveal the influence of an additional mesoporous TiO₂ (mp-TiO₂) layer on fabricating large-area perovskite solar cells using TiO₂ as the electron transport layer, we have conducted a comprehensive study on the solution-processed PSCs with or without an additional mp-TiO₂ layer. Photoemission spectroscopy measurement indicates that, compared with the compact TiO₂ (cp-TiO₂) layers, the mp-TiO₂ layers possess a slightly larger work function, which will improve the electron extraction efficiency at the perovskite-TiO₂ interface. The PSCs with an additional mp-TiO₂ layer exhibit better performances than those with only a cp-TiO₂ layer. They suffer from a smaller efficiency loss when enlarging the device area from 0.16 to 1.44 cm² and exhibit a better long-term stability. About 89% of the initial efficiency is retained after keeping in dry air for 1000 h for the device with an active area of 1.44 cm². For both cases, increasing the active device area is beneficial to long term stability, photoluminescence measurement indicates that this is result from the degradation of perovskite films starts at the margin of the cells. Our work implies the indispensable role of the additional mp-TiO₂ layer for optimizing the performances of large-area PSCs using TiO₂ as the electron transport layer.

The present study focuses on the adsorption property of zeolite material prepared from fly ash for NO_x, CO and other harmful air pollutants. X-ray diffraction (XRD) pattern of zeolite shows formation of two phase namely, Analcime and Na-P1 (Na₆Al₆Si₁₀O₃₂. 12 H₂O). X-ray photoelectron spectroscopy (XPS) study reveals the adsorption of NO₂, NO, N₂O and CO pollutants on zeolite which are confirmed by core level XPS spectra of N 1s, O 1s and C 1s peaks. The two-zeolite phases have low silica content having acidic and thermal resistivity properties. These properties can be exploited in internal as well as external building environment for adsorption of harmful air pollutants.

In this study, Eu²⁺ doped and Nd³⁺ co-doped rare-earth strontium aluminates CaAl₂O₄:Eu²⁺,Nd³⁺ luminous phosphor was prepared by coprecipitation-sol-gel(CSG) and high temperature solid-state(HTS) method. The rare-earth strontium aluminates CaAl₂O₄:Eu²⁺,Nd³⁺ powder was investigated in terms of material composition, crystalline phase, morphology and luminescence property by x-ray diffraction (XRD), Scanning Electron Microscope (SEM), fluorescence spectrophotometer, long afterglow phosphors tester and CIE chromaticity respectively. XRD analysis shows that doping a small amount of rare earth ions in the raw materials had no effect on the crystal texture of CaAl₂O₄ and the required temperature of solid phase method is higher than CSG reaction. The images of SEM show that the particle size of the phosphor made by CSG is smaller and more uniform than that of HTS. The excitation spectrum of the luminescent phosphor is a 240–360 nm broad band caused by ground state 4f⁷(⁸s_7/2) to 4f⁶5d excited state of Eu²⁺ and the spectrum peaks of nanometer material moved to the longwave region slightly. The strong emission peak near 440 nm caused by excited state 4f⁶5d to the ground state 4f⁷(⁸s_7/2) of Eu²⁺ and also shifts to the longwave region slightly in keeping with the changes of the CIE coordinates. The luminous fiber prepared by the CaAl₂O₄:Eu²⁺,Nd³⁺ powder of CSG method have great optical and mechanical properties.

Deposition of Cu₂CoSnS₄ (CCTS) thin films from molecular ink by simple dip-coating is reported. Molecular ink consists of metal-thiourea complex dissolved in methanol. Shiny brown-black films are obtained by thermolysing the precursor films at 200 °C in air for 20 min. X-ray diffraction and Raman spectroscopy confirmed the formation of pure stannite CCTS. Films are smooth and continues. The molecular ink may be used for direct liquid coating of CCTS as absorber layer for solar cells.

Red mud was mixed with starch and granulated, then roasted by microwave to form microwave-activated granular red mud (GRM) adsorbent. In this work, pore-forming mechanism of microwave-activated GRM and its effect for the removal of a cationic dye (methylene blue, MB) from aqueous solution were investigated. The results of dielectric properties of GRM and red mud in microwave field reveal that the addition of starch can effectively improve the microwave absorbing properties of the GRM sample. In addition, it is found that microwave-activated GRM adsorbent contains more pores and larger BET surface area than conventional-activated GRM adsorbent. The pore-forming mechanism of GRM by microwave activation is explained by the existence of temperature gradient and good absorbing properties of H₂O vapor and starch. The adsorption experiment results show that the MB removal rate of the microwave-activated GRM can reach 82% within 15 min, while the conventional-activated GRM requires 180 min to reach the same MB removal effect when the initial MB concentration is 60 mg L⁻¹. Langmuir model is found to represent the adsorption isotherm of MB on GRM better than Freundlich model. The adsorption capacity at 25 °C is 16.005 mg MB/1 g GRM. Thermodynamic parameters depicte spontaneous and endothermic nature of adsorption. The kinetics study shows that pseudo-second order model matches well the kinetic data.

SiC/C₃N₄ composites have been prepared by cooling crystallization method in this work for photocatalytic degradation. The sample with appropriate SiC/C₃N₄ composition(1: 50) exhibited the best performance for photocatalytic oxidation of Rhodamine B, which achieves about 2.5 times efficiency improvement compared with the sample prepared by direct mixing method, and it is also 100 times and 2.3 times than the pristine SiC powder and C₃N₄ respectively. We attribute the great photocatalytic improvement to the increased BET surface area, enhanced light-absorption ability, longer carriers lifetime and more effective heterostructure in SiC/C₃N₄ composites prepared by cooling crystallization method. In addition, the photocatalytic degradation mechanism of RhB was discussed in detail, and the accelerated charge-carrier mobility contributes to the improvement as well.

Regardless of considerable advancements made on mass production of chemically exfoliated graphene nanosheets the quality, processing time, productivity, cost and environmental friendliness remain key challenges for their commercialization. Here, we report a green, economical and fast exfoliation approach for the synthesis of highly crystalline graphene sheets by means of carbonated water assisted exfoliation based on its freezing—expansion property. The obtained graphene sheets were characterized by x-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM) and UV–visible spectroscopy. The above mentioned characterization tools marked the synthesis of highly crystalline and defect-free mono to few layer graphene sheets. The synergistic effects of both sonication and freezing-expansion property of carbonated water have realized the exfoliation of graphite into graphene nanosheets in actual practice.

A study on the flexural performance of 6-ply unidirectional hybrid composite laminates reinforced by carbon and basalt fibers is presented in this paper. The hybrid composites were fabricated following the resin transfer molding (RTM) process in an inter-ply configuration with varying plies of basalt fibers added to the surface of carbon laminate. Three-point bending test was carried out according to ASTM D790-10 at a span to depth ratio of 32. The laminates were examined by optical and scanning electron microscopy(SEM), which enabled a better comprehension of the failure modes. The results showed that various failure modes occurred through almost all of the layers and mainly concluded fiber buckling on the compressive side, shear failure on the middle layer, and fiber pull-out on the tensile side. Flexural properties of hybrid composites were strongly dependent on the basalt fibers added to the laminate. When adding two layers of basalt fibers to the laminates, flexural strength of hybrid composites increase most, and it can be seen that the flexural modulus decreased with increasing percentage of basalt fibers. And the experiments showed a positive hybridization effect by substituting carbon fibers with basalt fibers. Here, hybridization of carbon and basalt fibers can improve the balance of the mechanical properties of carbon fiber reinforced polymer(CFRP), thereby extending its application scope and reducing the cost.

Conventional shape memory programming involves, heating the material above the glass transition temperature (T_g), deforming to the desired shape, cooling below T_g and unloading to fix the temporary shape. However, for applications in large scale structures (e.g. deployable space structures), this process of deforming at high temperatures becomes a time, labor and energy expensive process. The reversible plasticity shape memory (RPSM) effect is an alternate programming approach wherein the material is plastically deformed (cold programmed) to a temporary shape at temperatures well below the transition temperature, preferably at room temperature. In this paper, the shape memory behavior of cold-programmed carbon-fiber reinforced carbon-nanotube (CNT)/epoxy laminates is investigated. The addition of carbon-fiber in a cold-programmable epoxy matrix resulted in significant changes in the glass-transition temperature and subsequently in the cold-programmability of the composites. So, in order to realize RPSM effect at room temperature, trials were made to optimize the glass transition region of the composites by varying the material constituents. Specimens of different laminate configurations with/without CNT reinforcement were fabricated to study the shape-memory behavior under flexure. The addition of 1 wt% CNT resulted in a slight increase in T_g but had no effect on the cold-programmability of the composites. Results reveal that all specimens show 100% shape-recovery. The laminate configuration had a considerable effect on the shape-fixity since the initial elastic recovery after unloading is dominated by the fiber reinforcement. CNT addition resulted in an improvement or no effect in shape-fixity and mechanical properties depending on the laminate configuration.

This paper is about tailoring high permittivity of multi-walled carbon nanotubes/silver nanoparticles (MWNT-AgNP) filled polyvinyl alcohol (PVA) nanocomposites at low frequency. PVA/MWNT-AgNP nanocomposites were synthesized via solution-casting technique at low MWNT content with different loading of AgNP. The nanocomposites showed a significant increment in ac conductivity, σ_ac, and dielectric permittivity, ε' by two orders of magnitude as compared to pure PVA. The maximum ε' value was achieved about 600 at 1.0 wt% of AgNP due to the increased charge carriers density and high interfacial polarization within the nanocomposites. The relaxation frequency was shifted towards a higher value with the increased of AgNP content while the relaxation time was decreased by 40%. Field emission scanning electron microscopy (FESEM) images showed the enhanced distribution of MWNT in the presence of AgNP to provide conductive pathways in the matrix. This was confirmed by energy-dispersive x-ray (EDX) analysis and ultraviolet-visible (UV–vis) spectroscopy. As a result, PVA/MWNT-AgNP nanocomposites have great potential for electrical applications such as cable accessories, high charge-storage capacitor and electromagnetic interference shielding materials.

Particulate composites based on ferrite and ferroelectric phase viz. cobalt zinc ferrite (Co_0.8Zn_0.2Fe₂O₄) and bismuth sodium titanate (Bi_0.5Na_0.5TiO₃) were synthesized using solid state reaction method. The formation of diphase composite was established using x-ray diffraction. Field emission scanning electron microscopy was used to study the microstructure of the composites, exhibiting fine blending of constituent phases in the composites. Dielectric behaviour of the composites was studied as a function of temperature and frequency. Variation of dielectric constant with temperature exhibits a shift in Curie temperature with increase in ferrite content. Usual dielectric dispersion is observed for the composites with increase in frequency. The consequence of addition of ferrite phase on ferroelectric and magnetic properties of composites was studied. All composites exhibit typical ferromagnetic hysteresis loops. Magnetoelctric coupling in the composites was confirmed by measuring magnetoelctric voltage coefficient (α_ME). The maximum α_ME of 7.11 mV cm⁻¹-Oe was obtained for 10% Co_0.8Zn_0.2Fe₂O₄—90% Bi_0.5Na_0.5TiO₃ composite.

In this article, the effect of elevated temperature on the rheological properties of grease-based magnetorheological fluids (G-MRFs) with the focus on long-term storage lifetime has been investigated. These G-MRF samples were subjected to accelerated heat aging process for the estimation of thermal stability and useful lifetime prediction. The well-known Arrhenius-Weibull relationship with a modified Powell-Beal conjugate gradient (CGP) algorithm was employed to model the 'life in service' for the achievement of possible life distribution at different temperature conditions. By defining the failure criteria of G-MRF samples as a maximum reduction of either viscosity or shear stress by more than 10%, the underlying degradation mechanism was revealed through Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analysis. Based on the statistical inference from accelerated life test (ALT), the life expectancy of G-MRF under nominal operating temperature is estimated to be 15.2 years, which outpaces the capability of most industrial applications. Experimental results showed that the performance of shear stress is more likely to degrade under long-term treatment of high temperature in comparison with low temperature. Thus, it is suggested to store the G-MRF at relatively low temperatures for longevity extension and reliability improvement.

The flow properties of carbonyl iron (CI) and electrolytic iron (EI) micro-particles based magnetorheological fluids (MRFs) were studied under steady shear conditions at different applied magnetic field strengths (B). The CI particles were spherically-shaped having a wide size distribution ranging from ∼0.2 to ∼3 μm whereas the EI particles were irregularly-shaped with much bigger particles of sizes between ∼20 μm and 80 μm. To prepare the MRFs, 40 wt% each of CI and EI micro-particles were separately dispersed in silicone oil. In the MRFs the particles do not contain any surfactant/coating and the MRFs do not include any stabilizers in them. According to the magnetorheological results, although the yield strength (τ_Y) and viscosity (η) of both MRFs increase with increase in B, there is deviation from the parallelism in increase of τ_Y and η with B. This suggests that τ_Y and η depend strongly on the physical parameters of Fe-particles such as the shape, size and saturation magnetization. The effect of saturation magnetization on steady state shear response of the MRFs dominates over the effect of shape and size of the particles.

In order to broaden the working frequency band of the piezoelectric energy harvester and improve the energy harvesting efficiency, a new two degree of freedom bistable piezoelectric vibration energy harvester is designed in this paper. It consists of a basic cantilever beam, a mass, a piezoelectric cantilever beam and magnets. The equivalent model of the system is established using lumped parameter method, and the two degree of freedom bistable motion equation is established considering the influence of electromechanical coupling. Using Matlab, the motion equation is calculated, and the curve of the system voltage with time and frequency is obtained. The voltage output characteristics of the system under bistable vibration and the influence of the stiffness and the mass of the basic cantilever beam on the output performance of the system are analyzed. Under the excitation of 0.3 g simple harmonics, the two degree of freedom bistable piezoelectric energy harvester is experimented using one-way frequency-increasing sweep. The results show that the maximum output voltage of the two resonance band of the energy harvester is 26 V and 13 V. Compared with the single degree of freedom bistable structure, the frequency band is widened by 10 Hz. In addition, reducing the stiffness of the basic cantilever beam and increasing the mass of mass block are all beneficial to broadening the working band of the harvester.

This contribution reports a comprehensive investigation into the structural, electronic and thermal properties of bulk and surface terbium dioxide (TbO₂); a material that enjoys wide spectra of catalytic and optical applications. Our calculated lattice dimension of 5.36 Å agrees well with the corresponding experimental value at 5.22 Å. Density of states configuration of the bulk structure exhibits a semiconducting nature. Thermo-mechanical properties of bulk TbO₂ were obtained based on the quasi-harmonic approximation formalism. Heat capacities, thermal expansions and bulk modulus of the bulk TbO₂ were obtained under a wide range of temperatures and pressures. The dependency of these properties on operational pressure is very evident. Cleaving bulk terbium dioxide affords six distinct terminations. Bader's charge distribution analysis for the bulk and the surfaces portrays an ionic character for Tb-O bonds. In an analogy to the well-established finding pertinent to stoichiometric CeO₂ surfaces, the (111):Tb surface appears to be the thermodynamically most stable configuration in the nearness of the lean-limit of the oxygen chemical potential. For the corresponding non-stoichiometric structures, we find that, the (111):O + 1V_O surface is the most stable configuration across all values of accessible oxygen chemical potentials. The presence of an oxygen vacant site in this surface is expected to enable potent catalytic-assisted reactions, most notably production of hydrogen from water.

SnO₂ in the AgSnO₂ contact material is a kind of high hardness and almost insulated wide bandgap semiconductor material. In the process of use, the contact resistance is large and the temperature raise is great, so that the contact reliability is reduced and the electrical life is shortened. In order to improve the comprehensive performance of AgSnO₂ contact materials, based on the first principle of density functional theory, the electrical and mechanical properties of Y with different ratios doped SnO₂ contact materials are calculated. Through the analysis of energy band, density of state and elastic constant, the results show that when the doping ratio of Y is 0.167, the conductivity is the best; the hardness decreases, and the universal elastic anisotropy index is the smallest. Finally, in the experiment, SnO₂ powders with different doping ratios are prepared by sol-gel method, AgSnO₂ contacts with different doping proportions are prepared by powder metallurgy, and arc energy, contact resistance, density and hardness are measured. and the final simulation and experimental results are well matched.

The AC electrical conductivity σ_ac(ω, T) in polycrystalline ordered defect semiconductor compound p-CuIn₃Se₅ is studied, for the first time, in the low temperature range 120–180 K with alternating current in the frequency range from 600 kHz to 1 MHz. The conduction mechanism is explained by the process that can be ascribed to the tunneling transport mechanism such as the Overlapping Large Polaron Tunneling (OLPT). The analysis of the frequency exponent of AC conductivity s(T), obtained from the study of the AC electrical conductivity through $s(\omega ,T)={\left(\tfrac{\partial \mathrm{ln}({\sigma }_{ac}(\omega ,T))}{\partial \mathrm{ln}(\omega )}\right)}_{T},$ allows us to show agreement with the theoretical model of OLPT. Some important parameters such as the hopping tunneling distance R_ω and the density of states at the Fermi level N(E_F) are estimated and their temperature and frequency dependence discussed. An equivalent circuit model is proposed to fit impedance plots and the activation energies for the relaxation process are estimated. The relaxation time for the grain boundary contribution is studied by analyzing the behavior of impedance versus frequency at different temperatures. The deduced relaxation time is found to decrease with increasing temperature and obey the Arrhenius relationship.

The pseudopotential plane-wave method in the framework of density functional theory with the generalized gradient approximation for the exchange-correlation functional has been adopted to calculate the phase stability and thermodynamic properties of BSb under high pressure and temperature. The BSb compound transforms from the most stable zinc-blende phase to the rock-salt one and the pressure of the phase transition is around 60 GPa, which is in excellent agreement with the available theoretical data. The thermodynamic properties, such as bulk modulus, heat capacity, entropy, thermal expansion coefficient, Debye temperature, and Grüneisen parameter of BSb with stable zinc-blende structure are determined in the temperature range of 0–1200 K and the pressure up to the phase transition pressure. In addition, the electronic polarizability, plasmon energy, microhardness, melting temperature, and the thermal conductivity at 300 K are also predicted for BSb in zinc-blende structure. It is believed that these results will be quite helpful not only to understand the investigated properties of this less studied compound but also useful for the future applications in semiconductor based devices.

The introduction of Keggin-type polyoxometalate (POM) K₄SiW₁₂O₄₀ into the solvothermal synthesis system of Cu₃SnS₄ (CTS) led to the formation of a new CTS-POM particle. The structure and composition were characterized by x-ray diffraction, scanning electronic microscopy and transmission electron microscopy. The results revealed that the CTS-POM particles exhibit multiporous microsphere morphology, which was first observed in CTS materials. A possible growing mechanism was proposed based on POM concentration-dependent growth study of the microspheres. The photodegradation of RhB and H₂ production under UV–vis irradiation was done to evaluate the photocatalytic activities of the samples. The results indicated that the as-synthesized CTS-POM exhibited enhanced photodegration of RhB and photocatalytic H₂ generation compared to pure CTS particles, and the content of loaded POM has an important impact on the catalytic activity of CTS-POM. The 5% POM-loaded CTS microspheres reached the best photocatalytic activity in H₂ production. Meanwhile, increased stability of photocatalytic activity of CTS-POM was also observed.

Co-precipitation method was used to prepare spinel ferrites having composition Co_0.6Zn_0.4Y_xFe_2−xO_4, where x is 0.00, 0.025, 0.05, 0.075, and 0.10. The magnetic, dielectric and structural characteristics of all these prepared ferrites were determined. XRD (x-ray diffraction) results proved the cubic spinel structure of synthesized ferrites. The dielectric loss, dielectric constant and AC conductivity reduced by adding rare earth concentration. The role of grains and grain boundaries was studied by using impedance analysis. The resistance of grains and grain boundaries was measured from Cole-Cole plots. Soft nature of prepared ferrites was confirmed by magnetic characters. By increasing yttrium concentration, remanence and saturation magnetization were reduced while coercivity was increased. All these parameters suggest synthesized ferrites as the best candidate for high frequency applications.

In this work, we study the structural, martensitic and magnetic characteristics of all-d-metal Ni_35−xMn_35+xCo₁₅Ti₁₅ (x = 0, 1, 2, 3) alloys. The x-ray diffraction analysis confirms that the alloy system crystallizes as 5 M modulated and L1₀ non-modulated martensite with a small fraction of B2 austenite phase for x = 0. The proportion of austenite phase increases while the martensite phase decreases with increase in x, and B2 austenite phase becomes dominant for x = 3. Large endothermic/exothermic peaks with distinct thermal hysteresis in differential scanning calorimetry analysis indicate the martensitic/reverse martensitic transformations. The martensitic transformation temperature decreases considerably with increase in x. Thermal magnetization (M-T) curves show an abrupt variation in magnetization from weak magnetic martensite to ferromagnetic austenite near martensitic transformation temperature. M(H) loops measured at room temperature confirm the ferromagnetic behaviour of all the prepared samples. Isothermal magnetization (M-H) curves of Ni₃₄Mn₃₆Co₁₅Ti₁₅ at various temperatures show that the magnetic field can induce the magnetostructural transformation in this alloy. A magnetic entropy change of 11.3 J K⁻¹ kg⁻¹ is observed at room temperature (290 K) in Ni₃₄Mn₃₆Co₁₅Ti₁₅ alloy.

To study effects of strong spin-orbit interaction of Mo ions on magnetic properties, we fabricate ferromagnetic thin films of Mo_xFe_3−xO₄ spinel ferrite by sputtering method and measure magnetization M_S and magnetic anisotropy (MA). Results show that M_S decreases almost linearly with x indicating that Mo ions are in low-spin state, and that the effective uniaxial MA constant changes sign with x. To clarify the electronic and magnetic states of Mo ions, first-principle calculations are performed. The calculated results of M_S at low Mo concentrations are consistent with experimental ones, however, they show also existence of local moments on Mo ions. These results are reconciled by considering that the Mo local moments are canceled by a change in the spin polarization around Mo ions.

In this report, the temperature dependent magnetic properties of graphene oxide (GO) have been studied. The graphene oxide is prepared by modified Hummer's method. The formation and structural analysis are carried out using XRD and Raman spectroscopy. Fourier transform infrared spectroscopy (FT-IR) is used to detect the presence of various functional groups. The magnetization curves as a function of the applied magnetic field at temperatures 10, 50, 150, 250 and 350 K has been accomplished. We have observed that ferrimagnetism, paramagnetism in lower temperatures along with ferromagnetism and diamagnetism in higher temperatures exist in the multilayer graphene oxide. The transition of magnetic states of GO with changing temperature is discussed based on average anisotropy energy and coupling interactions. The wrinkled structure and the defects due to the surface functional groups play a significant role in shaping magnetism in GO. The ZFC-FC curves are also analyzed to explore the system further.

Spherical Fe nanoparticles (FeNPs) with diameter of ∼100 nm were prepared by evaporating carbonyl iron particles (CIPs) using RF thermal plasma in a large scale. The FeNPs presented smooth surface, good dispersity and excellent antioxidation performance, which could be homogeneously distributed in paraffin with a particle loading as high as 90 wt%. In comparison to the raw CIPs, the FeNPs showed enhanced resonance characteristics in both permittivity and permeability due to the particle size effect. It was found that the FeNPs/paraffin composite exhibited excellent microwave absorption in terms of small matching thickness and broad bandwidth. The percentage bandwidth with reflection loss ≤−10 dB for the Fe nanocomposite is larger than that for the carbonyl iron composite at any specified thickness in the range of 1.0 ∼ 2.5 mm. This work demonstrates that the synthesized FeNPs hold great promise for developing thin-layered absorbers with excellent microwave absorbing performance.

Sr_0.7Al_0.3Fe_11.4Mn_0.6O₁₉ was synthesized by sol-gel technique and sintered at varying temperatures 750 °C, 850 °C, 950 °C and 1050 °C for 5 h. We investigate the role of heat-treatment on the structural, magnetic and optical properties of Al–Mn doped strontium hexaferrite. XRD analysis indicates the formation of M-type hexaferrites with some traces of α-Fe₂O_3. The presence of two prominent peaks between 400 cm⁻¹ and 600 cm⁻¹ in the spectra of FTIR gives the possibility of the emergence of M-type hexagonal ferrites. FESEM micrograph shows that the grains of the prepared sample possess Plate-like hexagonal structure. EDX spectra confirmed the stoichiometry of the prepared sample. Recrystallization of the synthesized sample and formation temperature of 650 °C is observed in TGA analysis. Variation of the sintering temperature results in decrease of the band gap. Magnetic parameters were calculated from the M–H loop obtained from vibrating sample magnetometer (VSM). High value of coercivity (6750 Oe) is observed at 850 °C. Remanent and saturation magnetization decreases with increase heat-treatment temperature. The synthesized sample may be useful in perpendicular recording medium (PRM) and high frequency application.

The nano-sized of La_0.7Sr_0.3Mn_1−xCo_xO₃ (x = 0, 0.2, 0.4, 0.6, 0.8) (LSMCO) powders were synthesized using a simple sol-gel method. For measuring microwave absorption properties, micro-sized carbonyl iron (CI)/LSMCO composites were prepared with the weight ratio of 75:5. The composite materials in the form of paints were applied on an aluminum substrate with a coating thickness of 0.7, 0.9 and 1.1 mm, respectively. Phase analysis of the products, morphology observation of particles, analysis of the element composition, the magnetic properties of the powders and the electromagnetic (EM) wave parameters were determined using x-ray diffraction analysis (XRD), field emission scanning electron microscopy (FE-SEM), dispersive spectroscopy (EDS), magnetometer (VSM) and vector network analysis (VNA), respectively. According to SEM observations, the average diameter of the La_0.7Sr_0.3Mn_1−xCo_xO₃(x = 0, 0.6) powders is about 30 and 36 nm, respectively. Room temperature magnetization results show a soft magnetic and ferromagnetic behavior of the CI, LSMCO powder. The CI/La_0.7Sr_0.3Mn_0.4Co_0.6O₃ composite showed a maximum reflection loss of—9.6 dB at 11.38 GHz with the thickness of 0.9 mm. By increasing the thickness of coating from 0.7 to 1.1 mm, the average absorption properties were increased.

Crystal and magnetic structure of iron substituted La_0.7Ca_0.3Mn_0.5Fe_0.5O₃ manganite was investigated by powder neutron diffraction in the 10–300 К temperature range. It is established that the unit cell parameters at 300 K are a = 5.447(2) Å, b = 7.709(3) Å, c = 5.467(3) Å and they change vs. temperature with rates da/dT ∼ 1.3*10^–4 Å*K⁻¹, db/dT ∼ 1.7*10^–4 Å*K⁻¹ and dc/dT ∼ 1.6*10^–4 Å*K⁻¹, respectively. It was also realized the measurements of magnetization and electrical resistivity in the 5–300 K temperature range including in magnetic fields up to 1 T. Magnetic phase separation was observed. Upon the field increase the glass, T_g, and irreversibility, T_irr, temperatures decrease, while the magnetic ordering temperature, T_mo, increases. Upon the temperature increase both the residual magnetization, M_r, and coercive field, H_c, decrease. A complex frustrated magnetic state in which the long-range G-type antiferromagnetic phase coexists with the short-range ferromagnetic clusters was established. An average size of ferromagnetic clusters is D_av ∼ 20 nm. An anomalous temperature behavior of electrical conductivity for La_0.7Ca_0.3Mn_0.5Fe_0.5O₃ was found which confirms a transformation of various magnetic states. Different models of conduction mechanism were considered. The origin of the unusual magnetic state, the electrical conduction mechanisms, and the relationship between magnetic and electrotransport properties in this sample were discussed.

Surface effects and spin glass state have been studied in Co₃O₄ coated manganese ferrite (MnFe₂O₄) nanoparticles by using AC and DC magnetic measurements. Average crystallite size of Co₃O₄ coated MnFe₂O₄ nanoparticles was 7 nm as calculated by Debye–Scherrer's formula. Simulated ZFC/FC revealed higher value of effective anisotropy (K_eff) = 5 × 10⁶ erg cm⁻³ of these nanoparticles as compared to bulk MnFe₂O₄ due to enhanced surface effects. Temperature dependent saturation magnetization followed the Bloch's law. Temperature dependent coercivity showed sharp increase below 25 K due to strong surface anisotropy and exchange coupling at interface between ferrimagnetic core and antiferromagnetic surface. For frequency dependent AC-susceptibility, dynamic scaling law fit confirmed the spin glass behavior in Co₃O₄ coated MnFe₂O₄ nanoparticles. DC field dependent AC-susceptibility showed the suppression of energy barrier, reduced activation energy and decreased strength of interparticle interactions with increasing DC field. Slow spin relaxation in ZFC protocol further confirmed the presence of spin-glass behavior. All this analysis confirmed the existence of spin-glass behavior as attributed to disordered surface spins and interparticle interactions in these nanoparticles, which gets suppressed after the application of moderate DC field.

The dependence of magnetic and thermal transport properties on charge states of Mn and Co in LaMnO₃ and LaCoO₃, respectively, has motivated to perform a systematic study in the La_0.95Sr_0.05Co_1−xMn_xO₃ (0.00 ≤ x ≤ 1.00). Substitution of Mn at Co-site leads to a decrease in both the thermopower (α) and the electrical conductivity (σ) values. However, there is a concomitant increase in the magnetothermopower (MTP) values with an increase in Mn substitution close to paramagnetic to ferromagnetic transition temperature (T_C). We observe a tunability in the sign of magnetoresistance with an increase in Mn substitution. Thermal conductivity (κ) exhibits a weak magnetic field dependence with magnetothermal conductivity (MTC) peaking close to T_C for 0.50 ≤ x ≤ 1.00. A maximum MTP is observed close to T_C in x = 0.95 sample. The dependence of α on magnetic field is found to increase with the enhancement of T_C in the system. We conclude that Mn substitution at Co-site not only improves the T_C in the system but also increases the effect of magnetic field on thermal transport properties.

Photoluminescence (PL) spectrum provides the most conventional measurement for emission properties of GaN-based light-emitting diodes (LEDs), in which Fabry–Perot oscillations are often observed modulating the emission peaks. A fitting model for PL intensity accounting the microcavity between air/GaN and GaN/sapphire heterostructure was proposed to treat the PL spectra of different GaN-based LEDs, extracting key factors that implied the interfacial optical properties. This approach was successfully verified by measurements of spectroscopic ellipsometry, then was applied to quantitatively analyse the interfacial-defect-related distortion of dielectric properties. The extracted oscillation coefficient is sensitive to the change of interface qualities and reveals the optical properties of internal interfaces. The new method may also be applied to the other heterojunction LEDs.

Single crystal of La₂Si₂O₇:Ce (LaPS:Ce) was successfully grown by floating zone method for the first time. The structure of as grown sample is confirmed to be monoclinic with space group P2₁/c by x-ray diffraction and energy dispersive spectra. Its photoluminescence (PL) and scintillation properties of LaPS:Ce crystal were characterized through vacuum ultra-violet excitation and emission spectra, PL decay curve, x-ray excitation luminescence spectrum, γ-ray multi-channel spectrum and afterglow spectrum. Emission peaks of this material are around 3.5 eV and 3.3 eV, corresponding to the typical transition 5d → 4f of Ce³⁺. The PL decay time of LaPS:Ce is 29.3 ns. The light yield of the sample is determined to be about 5400 ph MeV⁻¹ with a low afterglow level. The trap states in LaPS:Ce are also studied through the thermally stimulated luminescence measurement.

The effect of trace ZrC on the wettability, microstructure and mechanical properties of Sn-9Zn composite solder alloy joints was investigated. The results indicated that the wettability of the Sn-9Zn based composite solder alloy was improved and the microstructure was refined by adding appropriate amount nanoparticle ZrC. The microstructure of Sn-9Zn based composite solder alloys consists of primary Sn and Sn-Zn eutectic, and the excellent wettability and refined microstructure can be obtained by adding about 0.06 wt% ZrC. The interfacial intermetallic compounds (IMC) layer in the Sn-9Zn based composite solder alloy joints consists of Cu₅Zn₈ and Cu₆Sn₅. IMC layer thickness of Sn-9Zn based composited solder alloys joints is increased with increasing ZrC content. The tensile strength and the shear strength of Sn-9Zn based composite solder alloys joints relate to the ZrC content, and the maximum mechanical properties of solder joints are obtained by adding about 0.06 wt% ZrC, and the fracture mechanism of the Cu/Sn-9Zn-(0-0.09) ZrC/Cu solder joints is ductile fracture.

A self-consistent first-principles calculation with a precise hybrid PBEsol functional, Density Functional Theory (DFT) have been used to investigate the stability, elastic, mechanical, electronic, acoustic and thermodynamic properties of the cubic perovskite Lithium Aluminate (LaAlO₃). An investigation of the stability showed that the computed lattice parameter LaAlO₃ is stable, results also show that the lattice of LaAlO₃ becomes more distorted and deviates from the hydrostatic behavior as pressure is increased up to 11 GPa, after this limit, the structure encounter a phase shift, which is seen from the nature of the thermal properties of heat capacity. LaAlO₃ is thermos conversion-efficient cubic perovskite with its strong phonon scattering interactions resides mostly unclear. The energy band structure appears to display an indirect band gap insulator, with Γ−R separating the valence and conduction bands. Pressure dependence of cubic elastic Moduli, elastic wave velocities, Debye temperature and the density of states of LaAlO₃ were calculated, our results appear to converge with available experimental data. The elastic constants reveal the fact that the crystal is stable and show nature of crispness. The thermal characteristics were computed within the hybrid functional PBEsol using the Debye-Waller model and response functions. Lattice dynamics investigation of the perovskite thermoelectric LaAlO₃ are investigated with the single-crystal first-principles simulations and compared against inelastic neutron scattering (INS) at 100 K. Our ab-initio calculations of LaAlO₃ show a free asymmetry in the first nearest-neighbor peak. In addition, our first principles calculations data reveal stiffer bonding at the anion sites, which is in good agreement with the partial phonon densities of states from INS. The 4-dimensional phonon-dispersion surfaces of LaAlO₃, have been mapped and it is found that the origins of the ionic potential an-harmonicity being responsible for the unique behavior and phonon properties of LaAlO₃. The latter results provide clear evidence for the anharmonicity phonon distribution associated with the resonant bonding leading to a ferroelectric nature.

We develop a properly parameterized, three-dimensional continuum-scale kinetic model for monitoring the surface morphological evolution of coherently strained heteroepitaxial thin films that captures the morphological response of epitaxially grown Ge thin films on pit-patterned Si{100} substrates. The model accounts for curvature-driven atomic diffusion on the film surface, biaxial lattice misfit strain in the film, and the wetting potential between the film and the substrate. Self-consistent dynamical simulations based on our model show formation of complex nanostructures on the epitaxial film surface, including nanorings at the rims of pits, a single quantum dot at the center of a pit, as well as multiple quantum dots inside pits with rectangular openings, consistent with experimentally observed nanostructures. Our simulation results reproduce the variation in the formed nanostructural features observed experimentally by properly varying the key experimental parameters, namely, the pit size and the pit geometry. Our study sets the stage for designing systematic experimental protocols toward precise control of complex nanoring and quantum dot patterns forming on surfaces of epitaxially grown coherently strained semiconductor thin films.

Single phase polycrystalline BaMn_1−xA_xO₃ (x = 0.01, A = Ru, Fe and Nb) ceramics samples with a rhombohedral (15R) $R\bar{3}m$ symmetry were prepared via a conventional solid-state sintering route. The microstructure of all the samples was porous, and the substitutions at B-site did not affect the microstructure of these ceramics. Undoped BaMnO₃ ceramics exhibited relatively lower impedance values at low temperatures. The observed capacitance and resistance values suggested that the grain region (activation energy = 0.138 eV ± 0.0275) was slightly more conductive than the grain boundary (activation energy = 0.1430 eV ± 0.0246). No electrode effect was observed for the BaMnO₃ ceramics at 10–320 K; however, all the B-site doped BaMn_1−xA_xO₃ ceramics showed a decrease in resistivity with an increase in temperature, suggesting a semiconductor-like behaviour. For Ru–doped ceramics, the observed activation energies for the grain, grain boundary and electrode regions were 0.151 eV ± 0.0313, 0.172 eV ± 0.0022 and 0.170 eV ± 0.0511, respectively. Impedance spectroscopy of Fe-doped samples at 300–320 K revealed bulk only response with an activation energy of 0.165 eV ± 0.0029. For the Nb-doped samples, the grain effect was dominant at 40–80 K, the electrode effect was dominant near room temperature, and at intermediate temperatures, the grain boundary effect appeared more active. The calculated activation energies for the grain, grain boundary and electrode were 0.018 ± 0.0196 eV, 0.092 ± 0.0106 eV and 0.092 ± 0.0062 eV, respectively. For the Nb-doped ceramics, impedance spectroscopy was performed at room temperature using In/Ga alloy electrodes and the extrinsic effect (i.e. electrode effect) was confirmed by applying a dc bias.

In this work, powders of a crystalline conjugated small molecule are thermally evaporated and electronic devices are fabricated to understand process property relationship. The conjugated small molecule possessing donor-acceptor-donor structure is deposited at various rates ranging from very low; 0.5 Å s⁻¹ to as high as 10 Å s⁻¹. It is observed that the chemical structure of 2,5-dithienyl-3,4-(1,8-naphthylene) cyclopentadienone (DTCPA) remains unaltered after thermal evaporation. It is also observed that there is a change in morphology and crystal orientation of the deposited films with a change in deposition rate. A growth mechanism concerning morphology is proposed based on the morphological and structural studies. As the deposition rate increases, there appears to be a gradual change in physical structure and molecular alignment. Optical properties such as UV-Visible absorption suggests that majority of the thermally evaporated films have considerable absorption spectra in the visible range. While photoluminescence studies suggest that 0.5 Å s⁻¹ film showed large emission at 700 nm whereas, all other films showed large emission at 540 nm. Current density versus voltage characteristics of DTCPA showed that at higher evaporation rate the curve no longer acts as rectifying diode, which is further explained by an increase in ideality factor. The photoelectric responses of these films indicate that deposition rates and therefore the film morphology has a profound effect on the energy band level of the film as indicated by the extracted device parameters. The DTCPA films deposited at 2 Å s⁻¹ exhibit the best response with an ideality factor of 3.8 and highest mobility of 0.27 cm² V⁻¹ s⁻¹ suggesting optimum deposition rate is one of the critical parameters for device fabrication.

To enhance corrosion resistance of sintered NdFeB magnets, Ni–Al₂O₃ nanocomposite coatings were prepared on the magnets by pulsed current-jet electrodeposition. The effects of average current density and nanoparticles on the properties of coatings were evaluated. The surface morphology, microstructure, adhesion strength, and corrosion resistance of coatings were characterized by scanning electron microscopy, x-ray diffraction, scratch tester, and electrochemical workstation, respectively. The results showed that proper increase of current density was beneficial to the performance of coatings, and that protective properties of coatings decreased when the current density exceeded 120 A dm⁻². Properties of coatings were enhanced by the addition of nanoparticles. Nanocomposite coatings showed better adhesion strength and corrosion resistance than pure nickel coatings.

Plasma immersion ion implantation (PIII) is an important technique for performing a shallow junction for microelectronic applications. This work describes the effect of nitrogen PIII on structural, morphological and optical properties of CdTe thin films. To optimize the implantation results, the experiments were carried out at different exposure times (0, 2.5, 5, 10, 15 min). Scanning electron microscopy (SEM) and energy dispersed x-ray (EDX) were used to investigate the surface morphology of CdTe implanted films. According to x-ray diffraction (XRD) analysis, a considerable change in structural parameters such as lattice parameter, internal stress, crystallite size and lattice strain are observed as a result of increasing the duration time of plasma immersion nitrogen ions implanted CdTe film. The energy gap (${E}_{g}^{opt}$) values of implanted films were estimated in terms of the first derivative of absorbance with respect to wavelength and found to be decreased with increasing PIII exposure time. The reduction in ${E}_{g}^{opt}$ values was explained and correlated with the change in microstructure parameters.

To improve the wear resistance of Ti6Al4V alloy, Ni-Cr alloy coatings with 40 at.%Ni were prepared on Ti6Al4V alloy surface by double-glow plasma surface metallurgy technique. The friction and wear behaviour of the coatings sliding against Si₃N₄ at room temperature and 500 °C were comparatively studied. The results show that the alloy coatings comprise a deposited layer, a diffusion-modified layer and a heat-affected zone. The deformed deposition layer plays an anti-friction effect as a soft film. The tribological behaviour of diffusion layer is abrasive wear. Ni-Cr surface alloying process significantly reduces the friction coefficient of Ti6Al4V alloy and improves the wear resistance properties of Ti6Al4V alloy.

Titanium dioxide (TiO₂) is a widely studied photocatalyst for the degradation of organic pollutants from wastewater. This semiconductor is more potential than other semiconductors because of its stability, non-toxic, low cost, and commercial availability. A thin film of TiO₂:N 8% was deposited on a glass substrate using a sol-gel method with a spray coating deposition at a temperature of 450 °C. Precursors used in the synthesis of TiO₂:N 8% are titanium (IV) isopropoxide (TTiP), 2-propanol, acetic acid, methanol, and urea as the source of nitrogen doping. Thin film TiO₂:N 8% of subsequent deposition results at annealing at temperatures 400 °C, 500 °C, and 600 °C. Optical properties of TiO₂:N 8% were tested using a UV–vis spectrophotometer at 200–500 nm wavelength range. The photocatalytic properties of TiO₂:N 8% thin films were tested by degradation of a solution of Rhodamine B (RhB) 10 ppm using sunlight and UV C light for 3 h. The energy gap in thin film TiO₂:N 8% sequentially from Without Annealing, Annealing 400 °C, Annealing 500 °C, Annealing 600 °C has a value of 3.28 eV; 3.26 eV; 3.08 eV; and 2.95 eV, respectively. The material TiO₂:N 8% without annealing has a grain shape having a diameter of 0.5 μm to 1 μm, while for TiO₂:N 8% annealing 400 °C has the same grain shape without annealing. The composition of nitrogen atoms in the TiO₂:N sample of 8% by 0.2%. The efficiency of degradation shows the properties of TiO₂:N 8% photocatalyst with annealing for the better. The degradation process using 400 °C annealing temperature yields a thin film TiO₂:N 8% with better properties under UV C lamp of 89.22% in 180 min. Annealing temperature increase yields TiO₂:N 8% thin film with improved photocatalyst properties in sunlight with an annealing temperature of 600 °C at 79.30% in 180 min.

Two-dimensional heterostructures of atomically thin monolayer generated considerable interest for developing novel optoelectronic devices. Here, we report direct growth of MoS₂/WS₂ heterostructures by controlled sulfurization of DC sputtered thin films and CVD growth optimization. We have established the processing window for direct growth of MoS₂/WS₂ stacked heterostructure on SiO₂/Si substrate. Spatially resolved Raman and photoluminescence mappings are performed to confirm individual MoS₂, WS₂ and heterostructure growth. Experiments conducted at various temperatures along with areal distribution analysis of heterostructure revealed accurate processing window (700 °C–720 °C) for heterostructure growth of MoS₂/WS₂ while slightly lower or higher temperature favor MoS₂ and WS₂ monolayer growth respectively. The investigated growth by combining DC sputtering of metal films and controlled sulfurization in CVD provide the platform to fabricate 2D layered heterostructures for the next generation requirements.

Improvements in electrodeposited cuprous oxide (Cu₂O) junction devices could contribute to development of a wider range of affordable and environmentally friendly electronic devices. In this regard, ability of controlling interfacial properties of contacts of Cu₂O thin films with other suitable materials will be a very important property. A study on interfacial properties of p-Cu₂O/Au and p-Cu₂O/electrolyte junctions was conducted using capacitance-voltage and current-voltage measurements. It was found that pH of p-Cu₂O film deposition bath has a significant effect on junction properties of Cu₂O. Particularly, flat band potential at p-Cu₂O/electrolyte interface and built-in potential at p-Cu₂O/Au interface were shifted positively by the increase of deposition bath pH of p-Cu₂O films. Also, it was revealed that the shift was more pronounce at p-Cu₂O/Au interface compared to that at p-Cu₂O/electrolyte interface. The observed shifts in flat band potential and built in potentials were correlated with the shifts in relative band edge positions at the interfaces and with the change in net surface charge on the interfacial layers. It was observed, for the first time, that built in potential at p-Cu₂O/Au junction can be controlled with bath pH of p-Cu₂O films so that the junction can make either ohmic or non ohmic. Further, it was found that surface modification of p-Cu₂O films with sulphidation reduces barrier height at p-Cu₂O/Au junction and make the contact ohmic irrespective of bath pH of p-Cu₂O films. We report here, for the first time, that relative band edge position at interfaces of electrodeposited p-Cu₂O junctions can be controlled with pH of film deposition bath and surface modification. This will be very useful in application of electrodeposited p-Cu₂O thin films in solar cells and other junction devices.

The main aim of this study is to elucidate the best CNTs suspension concentration in DMF that achieve good performance during EPD process. The suspension concentration prepared in the range of 0.1 to 1.0 mg ml⁻¹. The EPD process was performed at a constant condition with applied voltage of 150 V, 10 min deposition time and 10 mm of electrodes gap. The thickness and weight of each deposited samples were measured particularly. Besides that, the morphological characterization of the deposited samples was examined using scanning electron microscopy (SEM). The results showed that the suspension concentration of 0.5 mg ml⁻¹ gave the best deposition performance with 11.98 μm of deposition thickness and 0.9 mg of deposited CNTs. The concentration from 0.1 to 0.4 mg ml⁻¹ had lesser deposition due to lower CNTs loading in the suspension. Meanwhile the concentrations from 0.6 to 1.0 mg ml⁻¹ produced inconsistent result due to higher tendency of weak interaction among particles. In this study, the 0.5 mg ml⁻¹ suspension concentration is the most suitable condition for EPD process for thermal interface materials (TIM) with firm adhesion on heat spreader. Therefore, this preliminary result could be used for the fabrication of TIM heat removal in microelectronic devices.

Al doped ZnO (Al:ZnO, 1 at%) thin films of varying thickness are deposited on silicon (Si) substrates using sol-gel spin coating method. The thermally annealed films are characterized for structural, surface morphology, vibrational and optical properties. The room temperature x-ray diffraction (XRD) patterns reveal polycrystalline hexagonal wurtzite structure (space group: P6₃mc) having compressive stress. The root mean square interface width and fractal dimension of AFM images are used to quantify the surface morphology and is found to be decreasing with increasing film thickness. The refractive index increases with increasing film thickness. A correlation between surface morphology and refractive index has been noticed and is attributed to the densification of the deposited films with corresponding increase in film thickness. The presence of characteristic ${{{\rm{E}}}_{2}}^{{\rm{high}}}$ mode in Raman spectrum confirms the formation of hexagonal wurtzite phase in deposited films. The IR spectral analysis reveals incorporation of Al in to ZnO host lattice. The optical band gap decreases (3.24 eV to 3.15 eV), whereas the Urbach energy as a measure of disorder in deposited films increases with increasing film thickness.

Electrical discharge coating (EDC) process is one of the surface modification method to deposit electrode material (WC 50% Cu 50%) on the surface of the desired material. In the present study ZE41A magnesium alloy has been coated using this method to form hard layer on the surface to resist wear and corrosion. Compaction load, current and pulse on time were selected as input responses to study the coating characteristics in the form of metal transfer rate (MTR) and surface roughness (Ra). Response surface methodology (RSM) was used to design and analysis the experiment. The most significant EDC parameters were ascertained using analysis of variance (ANOVA). From the result, it can be found that the MTR increases with increase pulse on time and decreases with high compaction load, where as MTR increases with increase current, further increase in current MTR decreases. Surface roughness increases with increases in current, pulse on time and low compaction load and conversely it diminishes with low current, pulse on time and high compaction load. Layer thickness and morphology of coated surface was analyzed using scanning electron microscope (SEM) and elements presents on the surface were confirmed using energy dispersive spectroscope (EDS).

Abrasion failure is a bottleneck problem that restricts the applications of titanium aluminum (TiAl) based alloys. This work has developed a facile method to endow TiAl alloys with superior wear resistance. TiAl composites reinforced by serpentine materials have been prepared by spark plasma sintering (SPS). Microstructural characterizations show that serpentine is well distributed in TiAl alloy matrix. Tribological behaviors in terms of a high-temperature friction and wear tester indicate that the reinforced particles play a positive role in decreasing wear rates and friction coefficients. Together with wear debris and high-temperature oxides, lubricant particles easily form a lubrication layer on frictional interfaces, which can help repair and compensate the worn-out pits and grooves thereby leading to the optimal wear resistance with the lowest friction coefficient of 0.41 and wear rate of 1.97 × 10⁻⁴ mm³/(Nm) at 400 °C–600 °C. This work sheds insights into evaluating the practicability of serpentine as a desirable solid lubricant and providing guidance for designing other serpentine-reinforced composites.

The effect of Sn/Cu thickness ratio on the transformation rate of Cu₃Sn in Sn/Cu₆Sn₅/Cu₃Sn/Cu joint is investigated during different aging temperatures. The results show that Sn/Cu₆Sn₅/Cu₃Sn/Cu joint will transform into Sn/Cu₆Sn₅/Cu₃Sn joint as the Sn/Cu thickness ratio is 100/1. The thickness of Cu₃Sn (δ₁) decreases linearly with increasing aging time and the consumption rate of Cu₃Sn (ν₁) exhibites a parabolic relationship with aging temperature. This is due to the fact that the flux ratio (r) of the Cu atoms across the Cu₃Sn and Cu₆Sn₅ layers is less than 1.2. Sn/Cu₆Sn₅/Cu₃Sn/Cu joint will transform into Cu/Cu₃Sn/Cu₆Sn₅ joint as the Sn/Cu thickness ratio is 1/7.5. The thickness of Cu₃Sn (δ₂) increases linearly with square root of aging time and the growth rate of Cu₃Sn (ν₂) follows parabolic relationship with aging temperature. This is due to the fact that the value of r is more than 3.

The Al₂O₃–40%TiO₂ (AT40) coating doped with the different contents of Yttria-stabilized zirconia (YSZ) on mild steel prepared by plasma spraying was studied. The different compositions of the YSZ powders are varied by 8 wt% and 20 wt%. The coating with 20 wt% YSZ exhibits a smaller wear rate and better hardness property than that with 8 wt% YSZ, which could be found through the wear resistance and Vickers hardness tests. The YSZ addition promotes the formation of Al_0.1Zr_0.9O_1.95 and then increases the wear and hardness properties of the composite ceramic coating.

Friction stir processing (FSP) has been established as a solid state technique for fabrication of metal matrix composites (MMCs). In the present investigation, FSP was used to disperse zirconia in copper to obtain copper matrix composite (CMC). For fabrication, a groove of known dimension was machined on to the surface of the copper plate (6 mm thick) and compactly filled with zirconia. After closing the groove with a pinless tool, it was processed with same tool material which had pin. The microstructural evaluation was carried by optical and scanning electron microscope (SEM). Observed micrograph confirmed uniform dispersion of zirconia in the copper matrix. The stir zone (SZ) of the fabricated composite displayed equiaxed and fine grain structure. Mechanical properties of the composite were assessed by microhardness and tensile test. The hardness of the fabricated composite in SZ improved significantly as compared to as received copper. Grain size reduction and uniform dispersion of zirconia contributed to the improvement in hardness. The tensile strength and electrical conductivity of the fabricated composite were found to be less as compared to as received copper. The post-assessment of the tensile specimen showed a reduction in ductility. The decreased electrical conductivity of the composite was ascribed to more scattering of electrons due to increased grain boundaries and non-conductive nature of zirconia.

To study the effect of isothermal temperature and cooling rate on the phase transformation and microstructure evolution in SWRH82B steels, a thermal dilatometer was used in this study to generate the static continuous cooling transformation (CCT) and isothermal-transformation thermal-expansion diagrams. In addition, scanning electron microscopy was used to analyze the effect of process parameters on microstructural transformation in the steel specimens. The results suggest that with a decrease in the isothermal temperature, the incubation time and duration of phase transformation gradually decreased; further, the content of non-lamellar pearlite in the microstructure gradually increased at room temperature. Compared with the time-temperature-transformation (TTT) diagram of SWRH82B steel subjected to conventional process conditions (rapid cooling before isothermal treatment), the incubation periods observed in this study were significantly shorter. When the loop-laying temperature was 850 °C, austempering temperature was 630 °C, and cooling rate was 5 °C s⁻¹, the incubation time and phase-transformation duration of the experimental steel were 9.60 and 28.52 s, respectively. With an increase in the cooling rate, the incubation period gradually increased, while the phase-transformation duration initially increased and then decreased. The room-temperature microstructure, obtained by austempering at 630 °C for 300 s, was mainly composed of well-distributed lamellar pearlite. With an increase in the cooling rate, the pearlite interlaminar spacing gradually reduced. However, the room-temperature microstructure, obtained by austempering at 550 °C for 300 s contained a large proportion of non-lamellar structures and the distribution of pearlite became disorganized.

In this work, the universal curve, critical behavior and magnetocaloric effect of the intermetallic compound Mn_0.92Sn_0.08CoGe around room temperature have been investigated. Magnetic data indicate that Mn_0.92Sn_0.08CoGe exhibits the characteristic of second-order transition around the room temperature 286 K. Moreover, the universal curve, well fitted by a Lorentz function, further proves second-order nature of the transition. The critical exponents obtained from various techniques such as modified Arrott plot (MAP), Kouvel-Fisher (KF) method, and critical isotherm analysis (M(T_C)) are found to basically fulfill the Widom scaling relation: δ = 1 + γ/β and obey the scaling equation of M (H, ε) = ε^βf_±(H/ε^β+γ), revealing the extracted critical exponents are reliable. The obtained critical exponents are close to the prediction of the mean-field model, suggesting the existence of long-range magnetic interactions coupling with the exchange distance decaying as J (r) ≈ r^−4.4.

The effect of SiC nanoparticles (NPs) addition on the microstructure, thermal and tensile properties of Sn–Zn–Ag solder alloy (SZA822) was studied. Mechanical mixing technique has been utilized to disperse SiC in SZA822 at 673 K for 3 h. Microstructure analysis revealed the plain SZA822 and SZA822–0.5 SiC composite solders are mainly composed of Sn, IMCs of Ag₃Sn & AgZn and Zn. But, after SiC addition, Ag₃Sn particles were refined while AgZn partially dissolves in the Sn-matrix. One endothermic peak appeared in each solder alloy which confirms one-step melting. The melting temperature is maintained at the SZA822 level. Tensile results showed that the levels of the stress-strain curves were sensitive to the values of deformation temperature T_d, strain rate $\dot{\varepsilon },$ and SiC loading. The ultimate tensile strength (${\sigma }_{UTS}$) increases while total strain (ε_T) decreases with SiC loading. So, SiC NPs act as a reinforcing agent. The strain rate sensitivity index (m) of composite solder was 0.09 and for SZA822 it was 0.11. Finally, the value of the activation energy Q of composite solder was 73.7 KJ/mole which is higher than that of SZA822 (61.7 KJ/mole). The Q values suggest that the dislocation motion mechanism is applicable in this work.

This work is focused on evaluation of mustard husk ash as reinforcement for aluminium matrix composite. Aluminium mustard husk ash composite has been prepared using powder metallurgy technique. Weight per cent of mustard husk ash in aluminium matrix was varied as 2.5%, 5%, 7.5% and 10% while compaction pressure was kept constant to study the effect of reinforcement on various properties of the composites like density, hardness and wear resistance. Scanning Electron Microscopy, Energy Dispersive Spectroscopy and x-ray Diffraction techniques were utilised to study the morphology of the composite. Density of the prepared composites decreased with increase in weight per cent of mustard husk ash. It was observed that composites containing 7.5% of mustard husk ash have better hardness and wear resistance.

In this study, ceramic coatings were deposited on AZ31 magnesium alloy by micro arc oxidation (MAO) technique in sodium phosphate electrolytes (Na₃PO₄.12H₂O) containing different concentrations of sodium hydroxide (NaOH) and borax (Na₂B₄O₇) under voltage of 420 V for 5 min. Hank's solution was used to investigate the corrosion behavior of the samples. Potentiodynamic polarization and electrochemical impedance spectroscopy were also employed. X-ray diffraction and scanning electron microscopy were applied for phase and microstructure characterization. The prepared MAO layers consisted mainly of ZnO and Mg₃PO₄. Results indicated that use of micro arc oxidation technique for coating may result in significant increase of corrosion resistance of magnesium alloy in Hank's solution. One of the important parameters which affects this coatings properties is the electrolyte composition which used in the process. The coating deposited by application of 10 g/l Na₃PO₄ + 1.5 g/l NaOH, exhibited the highest corrosion resistance in Hank's solution among the samples.

Ferromagnetic shape memory alloys Ni₄₅Mn₄₄Sn_11-xAl_x (x = 1, 2) were prepared by arc melting technique. The martensite transition, which is first order in nature, has been clearly observed through magnetic, differential scanning calorimetry and electronic transport measurements. Magnetic path dependent very large magnetic entropy change (19 Jkg⁻¹K⁻¹ and 14 Jkg⁻¹K⁻¹ obtained from decreasing and increasing field magnetization data, respectively) due to sharp increase of magnetization from weak magnetic martensite phase to ferromagnetic austenite phase has been observed for Ni₄₅Mn₄₄Sn₁₀Al₁ alloy. However, the observed large magnetic entropy change in Ni₄₅Mn₄₄Sn₉Al₂ alloy (20.6 Jkg⁻¹K⁻¹ and 19.2 Jkg⁻¹K⁻¹ obtained from decreasing and increasing field magnetization data, respectively) are found to be not much dependent on magnetic path. Thermal path dependent large negative magneto-resistance (∼ −15% and −24% at 288(C) K and 288(W) K, respectively, for 8 T applied magnetic field), due to difference in austenite and martensite phase fraction, has been found inside the martensite transition regime for Ni₄₅Mn₄₄Sn₁₀Al₁ alloy. From calorimertic measurement, the lattice entropy change for Ni₄₅Mn₄₄Sn₁₀Al₁ alloy due to the martensite transition has been observed to be nearly 55 Jkg⁻¹K⁻¹. The maximum adiabatic temperature change for Ni₄₅Mn₄₄Sn₁₀Al₁ and Ni₄₅Mn₄₄Sn₉Al₂ alloy are found to be −2.7 K and −1.2 K, respectively, for the change of magnetic field of 5 T. Magnetic field dependent isothermal resistivity does not change much outside the martensite transition temperature. Large decrease in resistivity by applied magnetic field has been observed inside martensite transition because of field induced conversion of martensite to austenite phase. The decreasing field isothermal magnetization and resistivity data do not follow increasing field data for having more austenite phase fraction than the field increasing path.

Separation of lithium and magnesium has always been a challenge due to their similar characteristics. In this regard, a two stage system was designed in which magnesium precipitated with ammonia and then magnesium from a diluted solution was extracted by D2EHPA in the presence of lactic acid. For this purpose, initial concentration of Magnesium, Ammonia volume, pH, Lactic Acid and D2EHPA concentration were the parameters which were investigated. The result was a high and desirable separation of these two elements. Usage of ammonia will only lead to precipitation of magnesium and a minor co-precipitation of lithium will occur. Presence of lactic acid in the extraction of magnesium by D2EHPA increased the yield of extraction and the highest observed yield for a concentration of 0.41 mol L⁻¹ of lactic acid and 0.32 mol L⁻¹ of D2EHPA was 88.6%. It should be noted that the amount of co-extracted lithium was never more than 3%. Finally, In order to determine the extraction conditions of lithium sole solution, the effects of contact time, pH, D2EHPA concentration and lithium initial concentration were studied.

This paper investigates the effect of homogenization treatment on microstructure, micro-hardness and corrosion behavior of AZ80 wrought Magnesium alloy. Homogenization at 523 K, 623 K, and 723 K were accomplished. Meanwhile samples were cooled in the furnace after 6 h and 12 h of diffusion annealing treatment. In this study, samples were characterized by using optical microscopy (OM) and scanning electron microscopy (SEM). Micro-hardness of the homogenized specimens were measured and electrochemical corrosion behavior of homogenized AZ80 alloy has been investigated. Attempt has been made to enhance both the hardness and corrosion resistance of the AZ80 Mg alloy by changing its microstructure during homogenization treatment. This investigation revealed that the hardness of Mg alloy is improved at 523 K–12 h holding time. It was also found that corrosion rates are minimum at higher homogenization temperature and lower holding time because of uniform distribution of secondary β-phases in Mg matrix, evidently shown in the microstructure of the heat treated Mg alloy. As a result, the homogenization treatment at 723 K for 6 h is desirable to enhance the corrosion resistance.

In this paper, AZ31/SiC nanocomposite was fabricated using squeeze stir casting method. 1 wt% SiC nanoparticles were added to the matrix using a novel powder injection system. The melt was stirred by two different speeds (430 and 600 RPM). The nanocomposite was solidified under the 80 MPa pressure. Some of the samples were cooled rapidly by water and some others were normally cooled by ambient air. Mechanical and microstructural properties of the fabricated nanocomposites were investigated. The results show that the controlled injection of nanoparticles using the gas can enhance the wettability and uniform distribution of nanoparticles. Moreover, increasing the stirring speed and cooling rate led to decreasing the grain size, increasing the uniformity of microstructure and improvement of mechanical properties. In the appropriate situation the yield stress, ultimate stress, elongation and micro hardness were increased by about 72%, 80%, 63% and 11%, respectively in comparison with monolithic AZ31 alloy.

Influence of cold work (CW) on volume of martensite (α') and rise in dislocation density was investigated by x-ray diffraction in the first stage. Then, the influence of CW on film resistance, passivation current density (i_p) and corrosion current density (i_corr) was investigated by electrochemical techniques. Also, mott-schottky (M-S) technique was used to investigate the semi-conducting behaviour and defect densities of passivating film. It is found that CW increase α' and dislocation density. It is also found that CW decreases charge transfer resistance (R_ct) and increases i_p and i_corr. Drop in R_ct suggests that the passivating film conductivity and consequently i_p and i_corr increased. Also, the relationship between the defects of the substrate and the defects of the passivating film and consequently its effect on i_corr has been established.

The effects of high energy shot peening on the microstructure and mechanical properties of TIG welded AZ31B magnesium (Mg) alloy joints were investigated. The surface characteristics, surface residual stress, tensile strength, grain size and dislocation density were characterized by the experimental observations. Results show that the surface defects were eliminated, tensile residual stress was turned into compressive residual stress and superior joining strength were obtained after HESP treatment under the pressure of 0.15 MPa. A nanoscale layer was obtained in the surface layer and the hardness was significantly increased in the surface layer. Large amounts of dislocations also generated with the aid of HESP treatment. All these factors contributed to the significant improvement in mechanical performance of the Mg alloy joints, leading to a notable enhancement (14.0%) in tensile strength of treated joints to 262.3 MPa over the joints without HESP treatment (230.08 MPa).

In order to improve mechanical properties of WE43A alloy and enhance production rates of castings in plastic deformation process, effects of double-procedure homogenization heat treatment (DHHT) on microstructure and mechanical properties of WE43A alloy were investigated and characterized by optical microscope (OM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), x-ray diffraction (XRD) and tensile tests. Results showed that eutectic Mg₄₁Nd₅ phase at grain boundaries completely dissolved into α-Mg matrix after the single-procedure homogenization heat treatment (SHHT) at 520 °C/8 h. However, eutectic Mg₂₄Y₅ phase with a small amount still existed in microstructure. After DHHT at 510 °C/12 h, eutectic Mg₂₄Y₅ phase completely dissolved into the matrix. After application of DHHT, the yield strength, ultimate tensile strength and elongation reached the maximum. The corresponding values were 110 MPa, 243 MPa and 21%. The morphology of tensile fractures varied from the mixed transgranular-intergranular fracture for the as-cast alloy to the transgranular cleavage fracture for the DHHT-treated alloy.

Recent years have seen researchers paying attention to the fabrication of porous structures by using additive manufacturing techniques suitable for the production of small batches. This paper focuses on the fabrication process and the compressive characteristics of a porous metal manufactured using the direct energy deposition (DED) process, which is a 3D printing technology for metals. Materials with structures containing internal pores were manufactured by spraying a mixture consisting of Ti6Al4V powder and a foaming agent (Na₂CO₃) onto a Ti6Al4V substrate, and subsequently fused with the substrate using a high-power laser beam. The ensuing molten pool undergoes rapid solidification, resulting in the formation of a metal layer. Before the molten metal solidifies, the carbon dioxide gas generated from Na₂CO₃ created pores inside the deposited layer. In this study, pored structures fabricated under various conditions were analyzed and compared from the viewpoint of compressive behavior. The results showed that the densities of the layered porous structures could be controlled by varying process parameters such as the laser power, scanning speed, powder feed rate, and mix ratio of the foaming agent. The most dominant parameters to obtain a pored structure were the amount of foaming agent and powder feed rate. The compression tests revealed that the porous materials manufactured using DED collapsed due to fracturing of the internal porous structures. After these structures fractured, the materials experienced densification, followed by crumbling. In addition, decreasing the laser power and scanning speed caused the compressive strength to decrease due to the high number of internal pores. Furthermore, before finally fracturing, the compressive strain decreased for specimens with increased porosity. The compression tests proved that the porous structure was able to effectively absorb compression loads.

CoMoCrSi superalloy powder (Tribaloy-T400) consists of intermetallic laves phase and primary eutectic phase of Co-rich solid solution. Processing of Tribaloy-T400 powder is carried out through high-energy ball milling (HEBM) technique to obtain a higher volume fraction of intermetallic laves phases. The feedstock is sprayed using high-velocity-oxy-fuel (HVOF) process on titanium grade-15 substrate. The coating microstructure is homogenized by microwave hybrid heating technique. Characterization of feedstock, as-sprayed and microwave fused coatings is done by using Scanning Electron Microscopy (SEM), Energy dispersive spectroscopy (EDS) and x-ray Diffraction (XRD). Porosity, surface roughness, microhardness, and bond strength are measured. Adhesive wear behavior of the coatings under the dry sliding condition is evaluated at an applied load of l0 and 20 N and temperature of 200, 400 and 600 °C Fused coating exhibit higher wear resistance than the as-sprayed coatings and substrate. The hard intermetallic laves phases which are amorphous (bulk metallic glass) in nature strengthen the coating at high temperatures.

5754 (AlMg₃) alloys have advantages such as good strength, perfect corrosion resistance and cold forming in addition to the low specific density. Because of these advantages, they are commonly used in automotive, chemical and food industries, and especially in the vessel and yacht industry. However, in spite of having such important and common areas of usage, it is very difficult to join Al and its alloys by traditional welding methods. This study focused on joining of 5754 Al alloy materials, which are hard to be joined by the traditional welding methods but have common areas of usage, by using the laser welding method. Laser welding method has many advantages such as the low heat input, deep penetration, low residual stress, and distortion compared to traditional welding methods. For this purpose, 3 mm thick 5754 Al alloy sheets were joined by using the laser welding method. The welding processes was carried out selecting three welding speeds (3, 4.8, and 6 m min⁻¹). The macrostructure, microstructure, hardness, tensile, and impact strength properties of the samples taken from the welded joints were examined. It was observed that micro-porosity and micro-void defects formed in the microstructure of the weld metal. The rate and size of these defects increased with increasing welding speed. The increase in the welding speed decreased the amount of the accumulated metal and the penetration rate. The mechanical properties were also negatively affected by the increase in the welding speed.

In recent years, the newly developed composite materials, such as Metal Matrix Composite (MMC), have been widely used. As MMCs have increasing applications, the investigations of their machining properties have become justifiable. Furthermore, high-speed machining processes are utilized to increase the productivity. In this study, the influence of high speed cutting parameters on the surface roughness and cutting forces of machined AL/SiC composite has been investigated. The cutting speed up to 2500 m min⁻¹, CO₂ cryogenic coolant and AL/SiC MMC consisting 15% silicon carbide were used. Design of experiment method using 5-level central composite design was also used. Results show that using CO₂ cryogenic coolant increases cutting forces 3%–8%, but improves the surface roughness by 19%–23%. The appropriate surface roughness is achieved in the presence of coolant while cutting speed is more than 1800 m min⁻¹, the feed rate is less than particle size per a tooth, and depth of cut is between 1 to 1.1 mm.