Table of contents

One of the great challenges of modern condensed matter theory is to develop reliable and practical methods for describing the electronic structure of strongly correlated materials fully from first principles. It has been known for a long time that the widely used Kohn–Sham density functional theory within the local density approximation (LDA) often fails for these systems. This paper describes the theoretical development of including electron correlations beyond the LDA with emphasis on ab initio methods, starting from the highly successful LDA+U and the many-body Green's function-based GW method to the state-of-the-art combination of dynamical mean-field theory and GW. Apart from reviewing the development so far we also present some previously unpublished results.

Crystal structures of α-Bi₂O₃ and β-Bi₂O₃ were calculated using Cambridge serial total energy package (CASTEP) based on the first-principles plane-wave ultrasoft pseudopotential method within local density approximation (LDA) and generalized gradient approximation (GGA) together with Perdew–Burke–Ernzerhof (GGA-PBE) and Perdew–Burke–Ernzerhof revised for solid (GGA-PBEsol). The structural parameter of α-Bi₂O₃ and β-Bi₂O₃ are in good agreement with previous experimental and theoretical data. All of the polymorphs were calculated for the total density of states (TDOS) and the partial density of states (PDOS) of Bi, O atoms. Density of states exhibits hybridization of Bi 6s and O 2p orbitals and the calculated charge density profiles exhibit the ionic character in the chemical bonding of this compound. The narrowed band gap (E_g) and red-shift of light absorption edge are responsible for the photocatalytic activity of Bi₂O₃ for water splitting application. The optical properties such as optical absorption and electron energy loss function were calculated to show the best structure among these polymorphs for the photocatalytic water splitting application.

Security ink using a carbon nanoparticle (C-dot)/PVA/chitosan-composite-based material has been successfully synthesized. The C-dot powder was prepared using a urea pyrolysis method. The precursors were synthesized using urea ((NH₂)₂CO, Mw  =  60.07 g mol⁻¹) and citric acid (C₆H₈O₇H₂O, Mw  =  210.14 g mol⁻¹) as the fuel and carbon sources, respectively. The C-dots were prepared by heating the precursor solution at 250 °C for 90 min. The security ink was fabricated using C-dots, polyvinyl alcohol (PVA, (CH₂CH(OH))_n, with Mw  =  ~20 000 g mol⁻¹) and chitosan as the dyes, resins and binders, respectively. The morphology and optical properties of the security ink were measured using SEM and EDX, a PL spectrometer and UV–vis spectroscopy. The viscosity properties of the security ink were measured using a viscometer. The characterization showed that the C-dots have a monodisperse particle size, a tetragonal structure and absorption spectra in the UV light region. It is shown that the PVA:chitosan concentration has a significant effect on the viscosity properties, so the viscosity is optimized for the security ink. In addition, the security ink was studied using a commercial printer, and the results show a good quality blue emission (450 nm) appearing under UV light exposure at 365 nm. The security ink C-dot/PVA/chitosan composite has potential applications in security, panel display, optoelectronic and optical devices on an industrial scale.

Copper film growth using thermal evaporation and annealing methods were studied using molecular dynamics simulations. The AlSiMgCuFe modified embedded atom method potential was used to describe the interaction of Cu–Cu, Si–Si and Cu–Si atoms. The annealing process, which was limited to atomic diffusion, repaired the crystal structure of the copper film. Our results showed that the thickness of the copper film catalyst substrate affected the initiation of the recrystallization process. A change of phase transition of copper atoms was observed after annealing. These phenomena were supported by knowledge of the radial distribution function and analysis of the crystal structure.

LiFePO₄ is commonly used as cathode material for Li-ion batteries due to its stable operational voltage and high specific capacity. However, it suffers from certain disadvantages such as low intrinsic electronic conductivity and low ionic diffusion. This study was conducted to analyse the effect of reduced graphene oxide (rGO) on the electrochemical properties of LiFePO₄/Li₂SiO₃ composite. This composite was synthesized by a hydrothermal method. Fourier transform infrared spectroscopy measurement identified the O–P–O, Fe–O, P–O, and O–Si–O⁻ bands in the LiFePO₄/Li₂SiO₃ composite. X-ray diffraction measurement confirmed the formation of LiFePO₄. Meanwhile, Raman spectroscopy confirmed the number of rGO layers. Further, scanning electron microscopy images showed that rGO was distributed around the LiFePO₄/Li₂SiO₃ particles. Finally, the electrochemical impedance spectroscopy results showed that the addition of 1 wt% of rGO to the LiFePO₄/Li₂SiO₃ composite reduced charge transfer resistance. It may be concluded that the addition of 1 wt% rGO to LiFePO₄/Li₂SiO₃ composite can enhance its electrochemical performance as a cathode material.

Magnesium alloys had been considered as promising biomedical devices due to their biocompatibility and biodegradability. In this present work, microstructure and corrosion properties of Mg–Zn–Ca–CaCO₃ porous magnesium alloy were examined. Porous metals were fabricated through powder metallurgy process with CaCO₃ addition as a foaming agent. CaCO₃ content was varied (1, 5, and 10%wt) followed by sintering process in 650 °C in Argon atmosphere for 10 and 15 h. The microstructure of the resulted alloys was analyzed by scanning electron microscopy (SEM) equipped with energy dispersive spectrometry data (EDS). Further, to examine corrosion properties, electrochemical test were conducted using G750 Gamry Instrument in accordance with ASTM standard G5-94 in simulated body fluid (Hank's solution). As it was predicted, increasing content of foaming agent was in line with the increasing of pore formation. The electrochemical testing indicated corrosion rate would increase along with the increasing of foaming agent. The porous Mg–Zn–Ca alloy which has more porosity and connecting area will corrode much faster because it can transport the solution containing chloride ion which accelerated the chemical reaction. Highest corrosion resistance was given by Mg–Zn–Ca–1CaCO₃-10 h sintering with potential corrosion of  −1.59 V_SCE and corrosion rate of 1.01 mmpy. From the microstructure after electrochemical testing, it was revealed that volcano shaped structure and crack would occur after exposure to Hank's solution

The mechanical properties of severely hot rolled Mg–1.6Gd (wt.%) alloys, such as hardness, ultimate strength, yield strength and ductility have been studied in the context of biodegradable implant materials. Unidirectional rolling (UR) and cross rolling (CR)were applied to prepare Mg–1.6Gd alloy ingots. In general, the mechanical properties of the alloy greatly improved after hot rolling due to a refinement of the microstructures. The relationship between the microstructure and mechanical properties is discussed in detail. Hot rolled samples were prepared in the temperature range of recrystallization(400–550 °C)with a speed of 10 mm min⁻¹ and a total reduction of 95% at 23.75% per pass, with an aim to characterize mechanical properties of the Mg–1.6Gd alloy such as hardness, ultimate strength yield strength and ductility. Tension and hardness testing were carried out and theVickers hardness values for the hot rolled samples were about 40–50 HV. The Vickers hardness increased with increasing hot rolling temperature. The maximum tensile strength and yield strength observed forUR samples were 197 MPa and 157 MPa, respectively and for CR samples, the values were 164 MPa and 107 MPa, respectively. Further, the maximum elongation for UR samples was 26% and, 17% for CR samples. Samples hot rolled with 95% reduction showed a higher ultimate tensile strength and ultimate yield strength than samples hot rolled with 30% reduction. The maximum elongation also differed between the two rates of reduction, where 95% reduction yielded an elongation of 26%, while a 30% reduction resulted in a maximum of 15%. The mechanical properties reported in this work highlight the benefits of Mg–1.6Gd as material for use in degradable implants.

Carbon nanotube (CNT) based nanocarbon foams (NFs) and the hybrid nanocarbon foams (HNFs) are fabricated in this work. The NFs are formed by using poly(methyl methacrylate) microspheres as a template to create micro-scaled pores. The cell walls are made of CNT networks with nano-scaled pores. The interconnections among CNTs are secured using graphene and nanographite generated via carbonization of polyacrylonitrile. The resulting NFs are ultra-lightweight, highly elastic, electrically and thermally conductive, and robust in structure. The HNFs are made by infiltrating thermoplastic polymer into the NFs in a controllable procedure. Compared to NFs, the HNFs have much higher strength, same electrical conductivity, and limited increase in density. The compressive strength of the HNF increased more than 50 times while the density was changed less than 10 times due to the polymer infiltration. It is found that the deformed HNFs can recover in both structure and property when they are heated over the glass transition temperature of the infiltrated polymer. Such remarkable healing capability could broaden the applications of the HNFs.

Transmission of Dirac fermions through a chip of graphene under the effect of a magnetic field and a time oscillating double barrier with frequency ω is investigated. Quantum interference within the oscillating barrier has an important effect on quasi-particle tunneling. The combination of both time dependent potential and magnetic field generates physical states whose energy is double quantized as reflected by the integer pair quantum numbers $(n,l)$ with a high degeneracy. The large number of modes that exist in the energy spectrum presents a colossal difficulty in the evaluation of physical results for arbitrary parameters. Thus we restricted our computations to weak time dependent perturbations so that we could limit ourselves to the central $(n=0)$ and two adjacent sidebands ($n=\pm 1$).

The crystalline germanium nanostructures were obtained on a silicon surface by the chemical vapor deposition technique using a germanium (IV) iso-propoxide ([Ge(OⁱPr)₄]) metalorganic precursor as a germanium source. As was observed, the one-dimensional (1D) germanium nanostructures on the silicon surface form without using a metal catalyst, meaning that the formation of 1D nanostructures is based not on a vapor–liquid–solid (VLS) growth mechanism, but on self-organization processes which take place on the silicon surfaces during the CVD process of germanium iso-propoxide pyrolysis. Our observation suggests that the non-catalytic growth of germanium nanocolumns is strongly dependent on the CVD process temperature. The germanium phase composition and morphology have been investigated by x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS), and high resolution scanning electron microscopy (HRSEM), respectively. Our results provide a new way to grow 1D germanium nanostructures without contamination by a catalyst, which the vapor–liquid–solid growth mechanism is known to cause, allowing for the application of such materials in micro- and optoelectronics.

Indium selenide is an emergent thermoelectric material. This work presents the synthesis and characterization of powdered indium-selenide (In₂Se₃) starting from elemental selenium powder and elemental indium in the form of beads, using a previous process of pulverization and subsequently submitting this powder to mechanical alloying in order to obtain the compound and to reduce the grain size, for this, the effect of the milling time of 30 h was studied. In order to characterize the powders obtained via mechanical alloying, x-ray diffraction and energy dispersive spectroscopy analysis were used. The morphological evolution was studied through scanning electron microscopy and to analyze the nanoparticles, transmission electron microscopy analysis was used. In this way, it is demonstrated that the desired compound is obtained from elemental selenium powder and elemental indium in form of beads which allows to reduce the costs of the raw material.

Candidates of precious metal catalysts, prepared in a facile and environmental way and showing high catalytic performances at low temperatures, are always highly desired by industry. In this work, large-scale Cu–Fe–Al–O nanosheets were synthesized by facile dealloying of Al–Cu–Fe alloys in NaOH solution. The composition, microscopic morphology, and crystal structure were respectively investigated using wavelength-dispersive x-ray spectroscopy with an electron probe microanalyzer, scanning electron microscopy, x-ray diffraction, and transmission electron microscopy. Furthermore, we found that the 2D Cu–Fe–Al–O nanosheets gave excellent catalytic performances in hydrogen production by methanol steam reforming at relatively low temperatures, e.g. 513 K.

Nanoparticles of TiO₂, ZnO and nanocomposite ZnO/TiO₂ were prepared via a co-precipitation method. The precursor powders were calcined in air at 400 and 500 °C for 2 h. Crystallite sizes of the calcined samples ranged from 11–43 nm. The XRD patterns of ZnO/TiO₂ powder showed two phases of anatase and wurtzite, with no ZnTiO₃ impurity phase. TEM images showed three types of particles in the ZnO/TiO₂ samples: a fine particle type of TiO₂ and submicron ellipsoidal and rod-like particles of ZnO. The energy gap (E_g) of the calcined powders was evaluated using UV–vis absorption spectra and found to be in the range of 3.15–3.60 eV. Photodegradation efficiencies of the prepared samples in methyl orange aqueous solution were investigated under UVA irradiation. The results showed that nanocomposite ZnO/TiO₂ calcined at 400 °C exhibited the highest apparent rate constant (k), and a higher capacity for methyl orange removal than TiO₂ and ZnO nanoparticles.

The following flexible structure PET-ITO/PEDOT:PSS/P3HT:SiNWs/Al has been fabricated. The effect of the concentration of silicon nanowires (SiNWs) on the transfer and transport properties of the elaborated hybrid nanocomposite P3HT:SiNWs is studied by photoluminescence (PL) and current–voltage measurements. From PL spectra, we conclude that lower SiNW concentration leads to a higher charge transfer rate. However, higher concentration leads to an increase in defects and aggregates. This result is correlated with SEM images and J-V measurement. According to the thermionic model, electric parameters such as ideality factor n and barrier height Ф_b were calculated. For the P3HT:SiNWs (1:1) ratio, barrier height and parallel resistance R_p were found to be 0.71 V and 6 KΩ, respectively.

Graphene sheets have been synthesized from single walled carbon nanohorns by one-step reaction with hydrogen peroxide. The obtained graphene sheets are in pure form and shows good electrical properties. As-synthesized graphene acts as dual function of support as well as reducing agent to prepare graphene-silver nanoparticle composite having uniform particle size of 6 nm. This method can easily be scalable to prepare graphene or graphene supported metal nanoparticle composites for versatile applications.

Poly(lactic acid) (PLA) fiber, owning to its biodegradability and biocompatibility, has extensive applications in many fields including textiles, and an enhanced antibacterial function can increase its application value. This work presents an innovative approach to prepare silver nanoparticles (AgNPs) using the hydrolytic degradation products of PLA fiber in the scouring process that contain reducing hydrolyzates (lactic acid and oligomers of lactic acid), and to functionalize PLA non-woven fabric using the resulting AgNPs. The preparation and application conditions of AgNPs were discussed. AgNPs with an average size of 80 nm were obtained at pH 9 and 90 °C with no use of an additional reducing agent in the presence of the use of polyvinyl pyrrolidone as a stabilizer, and exhibited good storage stability. PLA non-woven fabric was successfully treated with AgNPs using an impregnation technique at pH 4 and 70 °C, and the treated fabric exhibited excellent antibacterial activity against Escherichia coli and Staphylococcus aureus, even in the case of a low amount of Ag loading.

The specific properties of zinc oxide (ZnO) nanoparticles have attracted much attention within the scientific community as a useful material for biomedical applications. Hydrothermal synthesis is known as a useful method to produce nanostructures with certain particle size and morphology however, scaling up the reaction is still a challenging task. In this research, large scale hydrothermal synthesis of ZnO nanostructures (60 g) was performed in a 5 l stainless steel autoclave by reaction between anionic (ammonia or sodium hydroxide) and cationic (zinc acetate dehydrate) precursors in low temperature. Hydrothermal reaction temperature and time were decreased to 115 °C and 2 or 6 h. In batch repetitions, the same morphologies (plate- and needle-like) with reproducible particle size were obtained. The nanostructures formed were analyzed by powder x-ray diffraction, Fourier-transform infrared spectroscopy, energy dispersive x-ray analysis, scanning electron microscopy and BET analysis. The nanostructures formed were antibacterially active against Staphylococcus aureus.

Zinc oxide samples were synthesized at different reaction temperatures (70 °C–110 °C) by surfactant-free co-precipitation method using temperature gradient. Formation of hexagonal wurtzite structure of the ZnO samples is confirmed from x-ray diffraction (XRD) studies. This study further suggests reduction in crystallite size from 33 nm to 24 nm with increase in reaction temperature which is reconfirmed by field emission scanning electron microscopy (FE-SEM). Optical spectroscopy studies of these samples show significant peak shift towards higher energy with maximum photoluminescence (PL) emissions between 390 nm to 575 nm region of the visible spectrum. This evident inverse relationship between optical properties of ZnO nano particles and reaction temperature may be attributed to the temperature gradient causing rapid nucleation during the synthesis process. With these notable properties this study suggests that, ZnO nano particles may be useful for making Nano electronic devices, Sensors, Nano medicines, GATE Dielectrics, Photovoltaic devices etc.

The application of a Taguchi approach to the optimization of the precipitation reaction between Sm³⁺ and ${{{\rm{WO}}}_{{\rm{4}}}}^{2-}$ as a rapid procedure for the preparation of Sm₂(WO₄)₃ nanoparticles as a photocatalyst is evaluated. The effect of the prominent operating factors on the product are evaluated so as to yield the best synthesis conditions, leading to the finest product particles of the desired morphologies, which can turn the rather primitive precipitation reaction into a powerful tool for the preparation of nanostructured crystals of insoluble salts. The effects of the alteration of the studied factors on the final properties of the product are further evaluated through characterization techniques, including x-ray diffraction, energy-dispersive x-ray analysis, scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. The results of the study, together with the analysis of variance operations, revealed that through the control of samarium and tungstate concentrations, and temperature, considerable results can be achieved in terms of the product dimensions, morphology, purity and structure. Moreover, the photocatalytic behavior of the synthesized samarium tungstate nanoparticles for the photocatalytic degradation of methylene blue under ultraviolet light is investigated and compared with titanium dioxide as a well-known photocatalyst.

An oxygen-deficient nanosized ${\mathrm{TiO}}_{2-\delta }$, $\delta \,\sim 0.7$ sample was synthesized by a solvothermal method, and was characterized to have both ∼3 nm amorphous solid and ∼36–46 nm diameter rutile nanowires. Physical properties of the sample were investigated by measuring magnetic, specific heat, electrical resistance and magnetoresitance properties. DC magnetization M(H) data confirm ferromagnetic behavior previously reported for undoped TiO₂. Furthermore, M(T) dependence follows the power-law relation $M{(T)\propto (1-T/{T}_{C})}^{\beta }$ in the near-critical regime, yielding Curie temperature ${T}_{C}\,\sim 415$ K and critical exponent β = 0.2. Moreover, our results of AC magnetic susceptibility measurements suggest an additional phase transition at ${T}^{* }\,\sim 310$ K, presumably due to spin orientation. The metallic-like electrical resistance exhibits a distinct drop below ${T}^{* }$ with a strong thermal hysteresis in the temperature range 225–275 K. Specific heat in the temperature range 20–300 K is well described by the sum of contributions from acoustic phonons with Debye temperature 605 K and optical phonons with Einstein temperature 113 K. Below 10 K the specific heat divulges a large excess, which can be interpreted as an additional contribution originating from soft potentials.

The mechanism of sono-chemically synthesized mesoporous ZnS nanoparticles has been investigated. ZnS nanoparticles were synthesized with a facile and quick method. The sonication process was carried out for several times up to 60 min. The synthesized particles have been characterized with scanning electron microscopy, transmission electron microscopy, high resolution x-ray diffraction, UV–visible technique, diffuse reflectance spectroscopy, Brunauer–Emmett–Teller and Fourier transformation infrared spectroscopy. Based on x-ray diffraction patterns, crystallite size and lattice strain increase with sonication time. Adsorption–desorption results showed that applying the sono-chemistry synthesizing method in the aqueous atmosphere will cause a mesoporous structure. The obtained specific surface area of the synthesized mesoporous ZnS nanoparticles varied from 53 to 58 m² · g⁻¹. Also the surface areas created from the porosity of the particles varied from 27 to 29 m² · g⁻¹. Regarding these results, the mechanism of porosity formation during synthesis of nanoparticles has been explained. Photocatalytic behavior of the synthesized particles has been investigated for degradation of methylene blue from aqueous solution. Factors affecting this behavior have been discussed and it was found that interaction between opposing factors caused the specimen synthesized with 40 min sonication time has the best methylene blue degradation efficiency.

Left handed meta atoms are special class materials that characterized by the negative refractive index. In this paper, a left handed biaxial meta-atom is reported that has 5.81 GHz wide bandwidth and applicable for C-, X- and Ku-band applications. The meta atom is developed by an outer and the inner split ring resonator with inverse E-shape metal strips of copper, which are connected with the outer ring resonator that look like a mirror-shape structure. A finite integration technique based CST Microwave Studio is utilized to design, simulation and analysis purposes, where the Agilent N5227A vector network analyzer is utilized for measurement purpose. Measurements show that, the measured and simulated results are well complied together and negative index bandwidth from 3.27 to 6.55 GHz (bandwidth of 3.28 GHz) and 7 to 12.81 GHz (bandwidth of 5.81 GHz) along the z-axis wave propagation. The total dimensions of the designed structure are 0.2λ  ×  0.2λ  ×  0.035λ and the effective medium ratio 5, makes the proposed biaxial meta-atom is suitable for practical applications.

Natural mineral rutile sand is used for preparing titania (TiO₂) nanoparticles employing a cost-effective simple chemical method and mass production technology. Further the sulfur doped (S/TiO₂) and pure TiO₂ are produced from chemical precursor also. Different techniques are used to analyse the effect of sulfur dopant like x-ray diffraction, Fourier-transform infrared spectroscopy, Raman spectroscopy, x-ray photoelectrons spectroscopy, ultraviolet–visible spectra, photoluminescence, Brunauer–Emmett–Teller analyser, field emission scanning electron microscopy with energy-dispersive x-ray analysis, and high-resolution transmission electron microscopy. Under visible light, a useful procedure is followed on the sulfur-doped samples preparation, enhancing the charge carrier recombination, and reducing crystallite size. In the improvement of the efficiency of dye-sensitized solar cells, this dopant could open up vast opportunities; consequently, our work is extended to apply these prepared samples in standard dye-sensitized solar cells. The photoanode of dye-sensitized solar cells are made up of these prepared materials (S-doped TiO₂ and pure TiO₂) and compared with both commercial TiO₂ (P-25) powder, as well as commercially available paste (Dyesol). The S/TiO₂ nanoparticles on dye-sensitized solar cells exhibit enhanced ultra-violet visible light absorbance with increased photogenerated electrons and holes meanwhile reduce the recombination rate of charge carriers in dye-sensitized solar cells. Further, the overall power-conversion efficiency (η) and external quantum efficiency of the S/TiO₂ cells (η  =  4.32% and EQE  =  32%) is two times higher than that of pure TiO₂ cells (η  =  2.75% and EQE  =  16%).

The room temperature photoluminescence emission at 1.55 µm from InN/In_0.7Ga_0.3N dot-in-nanowire heterostructures, which was grown on self-assembled GaN nanowires on Si (1 1 1) under N-rich condition by plasma assisted molecular beam epitaxy, has been clarified in this paper. The morphology of the nanowires was uniform along the c-axis as proved by scanning electron microscope, each of the nanowires was grown individually and homogeneously without any coalescence phenomenon respectively. The nanowires dispersed on a silicon substrate showed very clear InN dot-in-nanowire structure by high resolution transmission electron microscopy. The structural properties of the individual InGaN nanocolumn were further investigated by high-angle annular dark field image analysis and energy dispersive x-ray spectrum, which confirmed the successful growth of InN quantum dot embedded in InGaN nanowire.

Titanium dioxide (TiO₂) nanopowders were prepared by the sol–gel process vie gelation at different pH values (6.8−12.5) in ammonia solution calcined at 500 °C for 2 h. The x-ray diffraction patterns showed that all samples exhibited a tetragonal anatase TiO₂ phase. The crystallite sizes increases from 10 to 14 nm and band gap energy ranges from 3.2 and 3.3 eV as the solution pH is increased from 6.8 to 12.5. The lattice constants increased with increasing the synthesized pH value, which implies also a decrease of the micro-strain. The highest blue emission peak centered at around 416 nm was observed for the pH 12.5 compared with low pH values in the photoluminescence spectra of the synthesized TiO₂ powders. Experimental results showed that TiO₂ nanoparticles synthesized at pH 12.5 exhibited the optimal structural and luminescence properties.

The crack growth and expansion characteristics of Fe and Ni were studied using the quasi-continuum approach based on the embedded atom method (EAM) potential. The crack growth and expansion characteristics of Fe and Ni were evaluated in terms of atomic stress fields and stress intensity factors. The simulation results showed that the strength of Fe and Ni obviously decreased with increasing crack length. However, at the same strain, the crack growth and expansion of Fe and Ni did not vary upon increasing the crack angle. Moreover, in cases with the same orientation I, it was found that Fe is more easily broken than Ni, but for cases with orientation II, the opposite was found.

In the present study, a successful attempt has been made on enhancing the properties of hybrid kenaf/coconut fibers reinforced vinyl ester composites by incorporating nanofillers obtained from coconut shell. Coconut shells were grinded followed by 30 h of high energy ball milling for the production of nanoparticles. Particle size analyzer demonstrated that the size of 90% of obtained nanoparticles ranged between 15–140 nm. Furthermore, it was observed that the incorporation of coconut shell nanofillers into hybrid composite increased water absorption capacity. Moreover, tensile, flexural, and impact strength increased with the filler loading up to 3 wt.% and thereafter decrease was observed at higher filler concentration. However, elongation at break decreased and thermal stability increased in nanoparticles concentration dependent manner. Morphological analysis of composite with 3% of filler loading showed minimum voids and fiber pull outs and this indicated that the stress was successfully absorbed by the fiber.

FePd₃-type alloys have attracted strong interest due to their unusual pressure-induced Invar behaviour characterized by anomalously low thermal expansion properties. However, little is known about the factors controlling their magnetization properties. Here we present a chemical vapour deposition approach which allows the encapsulation of FePd₃ alloys into a spherical type of carbon nanomaterial consisting of concentrically arranged distorted-carbon-layers. A dependence of the magnetic properties of this soft ferromagnetic phase on the crystal-grain-size is found by comparing the results in the present study with those reported in literature. The fabricated samples are characterized in detail by electron microscopy, x-ray and electron diffraction and magnetometry.

LiNbO₃ microcrystalline systems, possessing almost stoichiometric composition, were produced by varying the temperature and time parameters in the annealing processes following a mechanochemical reaction of raw powders. SHG from these samples, detected for every fundamental wavelength in the range 800–1300 nm, and being maximal at a certain wavelength, λ_max, for each sample, has been addressed to a random scattering of the induced nonlinear polarizations. Possible tuning of λ_max could be ascribed to control of composition and grain size of the sample. Random orientation of the produced nanocrystallites was verified since no dependence for SHG intensity on incident polarization was observed.

ZnO thin films were deposited onto glass substrate by sol–gel dip coating method. The initial sol concentrations were varied from 0.2 to 0.5 M. Zinc acetate dihydrate, ethanol and Diethanolamine (DEA) were used as staring material, solvent and stabilizer respectively. The evolution of structural, optical properties and methylene blue (MB) photodegradation of the as-deposited films on sol concentration was investigated. Rietveld refinements of x-ray patterns reveal that all the as-prepared thin films have a Zincite-type structure with grain orientation along to c-axis. The strongest sol concentration is favorable for the highest crystallization quality. However, the high preferred orientation factor (POF) occurs for 0.3 M sol concentration. The field emission scanning electron microscopy observations reveals nanofibrous morphology with different lengths. The nanofibers density increases with increasing sols concentrations until forming a flower-like morphology. The EDS analysis confirms the high purity of the as-deposited ZnO films. It is found that all films present good transparency greater than 95% in the visible range; the optical band gap is slightly reduced with the increase in sol concentration. The photocatalytic degradation is enhanced by 90% with the sol concentration. The K_app rate reaction increased with increasing sol concentration. The films stability is found to slightly decrease after the third cycle, especially for 0.5 M sol concentration.

This work deals with the effect of Cu doping on thermal stability of the structural properties of Y-stabilized ZrO₂ nanopowders and dopants' spatial distribution. The powders were synthesized by a co-precipitation technique, calcinated at T_c  =  500–1100 °C during 2 h and studied by x-ray diffraction (XRD) and transmission electron microscopy. Calcination at T_c  =  500 °C results in the formation of ZrO₂ nanocrystals with tetragonal phase predominantly. The shifts of XRD peak positions of Cu-doped powders to larger angles in comparison with those of Cu-free ones testify to the Cu presence inside nanocrystals. The T_c increase results in two main processes: (i) the non-monotonic shift of XRD peak positions and (ii) the phase transformation (tetragonal to cubic and both of them to monoclinic). This observation was explained by, at first, Cu atoms incorporation into the nanocrystal volume from the surface complexes (T_c  =  500–700 °C) and then their outward diffusion followed by the formation of crystalline CuO (T_c  >  700 °C). Phase transformation sets in at T_c  =  700 °C, when monoclinic phase appears. Its contribution rises till T_c  =  1000 °C. The mechanism of monoclinic phase formation is supposed to be consisted of the out-diffusion of interstitial Cu ions due to their shift from lattice sites. This promotes an appearance of the channels for Y out-diffusion via cation vacancies and results in phase transformation. The sintering process stimulated by CuO formation is proposed to be responsible for appearance of cubic phase at 1000–1100 °C.

SiO₂/Fe/SiO₂ sandwich structure films fabricated by sputtering were studied by varying the Fe layer thickness (t_Fe). The structural and microstructural studies on the samples showed that the Fe layer has grown in nanocrystalline form with (1 1 0) texture and that the two SiO₂ layers are amorphous. Magnetic measurements performed with the applied field in in-plane and perpendicular direction to the film plane confirmed that the samples are soft ferromagnetic having strong in-plane magnetic anisotropy. The temperature dependence of magnetization shows complex behavior with the coexistence of both ferromagnetic and superparamagnetic properties. The transport properties of the samples as studied through Hall effect measurements show anomalous Hall effect (AHE). An enhancement of about 14 times in the saturation anomalous Hall resistance ($R_{\text{hs}}^{\text{A}}$) was observed upon reducing the t_Fe from 300 to 50 Å. The maximum value of $R_{\text{hs}}^{\text{A}}$  =  2.3 Ω observed for t_Fe  =  50 Å sample is about 4 orders of magnitude larger than that reported for bulk Fe. When compared with the single Fe film, a maximum increase of about 56% in the $R_{\text{hs}}^{\text{A}}$ was observed in sandwiched Fe (50 Å) film. Scaling law suggests that the R_s follows the longitudinal resistivity (ρ) as, ${{R}_{\text{s}}}\propto {{\rho}^{1.9}}$, suggesting side jump as the dominant mechanism of the AHE. A maximum enhancement of about 156% in the sensitivity S was observed.

We demonstrate that gold nanorod arrays support LSPR modes which coincide with Frankel excitons in an organic J-aggregate complex forming plexciton hybrid states when tuned to within the strong coupling limit. The addition of graphene oxide modifies the strong coupling resonance conditions and Rabi frequency. This demonstrates that the formation of exciton–plasmon plexciton states in the strong coupling limit can be modified and potentially controlled through the introduction of graphene oxide which can have implications for energy harvesting or biosensor device design.

Y₂O₃:Eu³⁺ (YOE) material is an important photoluminescence (PL) material. In this paper, YOE nano-powder was prepared by the low-temperature combustion method (LTC) and sol-gel method (SG), and annealed with different temperatures, respectively. The influence of the preparation methods and annealing temperature on the optical properties of YOE were well studied. The as-synthesized nano-YOE samples were characterized by x-ray diffraction (XRD), PL spectra, and Fourier transform infrared spectroscopy (FTIR). Results show that with the increase in annealing temperature, the charge transfer band (CTB) of samples blue-shifts and shows higher intensity. FTIR results indicate that low emission intensity decreases luminescence intensity and deteriorates the optical properties of nano-YOE. We also studied the spectral intensity changes before and after laser-induced, which shows the intensity of significant changes over time.

Objective. SDF-1 loaded galactosylated chitosan (GC) nanoparticles for liver targeting were synthesized by electrospraying technique, and its biocompatibility and liver targeting effect were evaluated. Method. The SDF-1 loaded GC nanoparticles were constructed and its morphology was observed by the scanning electron microscopy (SEM). Hepatocytes were harvested and cocultured with the nanoparticles, and the albumin secretion and urea synthesis were detected by enzyme-linked immunosorbent assay assay, the concentration of lactate dehydrogenase (LDH) and tumor necrosis factor-α (TNF-α) was also measured. Finally, the nanoparticles were injected intravenously through the caudal vein of rat, and its liver targeting effect was evaluated. Result. SEM showed the nanoparticles distributed uniformly, with an average diameter of 100 nm and a regular spherical shape. There was no significant difference in urea synthesis, albumin secretion, concentration of LDH and TNF-α between two groups (p > 0.05). The nanoparticles were significantly accumulated in the liver tissue after its injection, but seldom fluorescence signals were observed in the lung, spleen, heart and kidney. Conclusion. The SDF-1 loaded GC nanoparticles showed uniform distribution, good biocompatibility and liver targeting effect, and suggested its potential application as a liver targeting delivery system.

A biocompatible method for synthesizing of highly disperses gold nanoparticles using Ferulago Angulata leaf extract has been developed. It has been shown that leaf extract acts as reducing and coating agent. Various spectroscopic and electron microscopic techniques were employed for the structural characterization of the prepared nanoparticles. The biosynthesized particles were identified as elemental gold with spherical morphology, narrow size distribution (ranged 9.2–17.5 nm) with high stability. Also, the effect of initial ratio of precursors, temperature and time of reaction on the size and morphology of the nanoparticles was studied in more detail. It was observed that varying these parameters provides an accessible remote control on the size and morphology of nanoparticles. The uniqueness of this procedure lies in its cleanliness using no extra surfactant, reducing agent or any capping agent.

This work proposes chemically synthesized Gd doped ZnS nanoparticles based system for potential use as contrast enhancing agent for both optical fluorescence imaging and magnetic resonance imaging. Two different Gd doped ZnS nanoparticle systems were synthesized. These systems were (i) graphene oxide–Zn_1−xGd_xS (x = 0.1, 0.2 and 0.3) nanoparticle composites and (ii) chitosan coated Zn_1−xGd_xS (x = 0.1, 0.2 and 0.3) nanoparticles. Gd formed solid solution with ZnS in all the six as-synthesized samples. Gd doped ZnS nanoparticles in both cases exhibited both longitudinal and transverse relaxivity values. A clear dependence the relaxivity values on the composition of the nanoparticles and the nanoparticle environment (presence and absence of graphene oxide) was observed. Between the two cases, values of the longitudinal and transverse relaxivity were higher for the graphene oxide–Zn_1−xGd_xS composites. It is also shown that Gd doped ZnS nanoparticle can be used for fluorescence imaging also. Gd doped ZnS nanoparticle exhibited biocompatibility towards the MCF-7 cell line.

The paper gives the results of studying the structure of porous condensates of Fe + NaCl composition, chemical and phase compositions and dimensions of nanoparticles produced from the vapor phase by EB-PVD. Iron nanoparticles at fast removal from the vacuum oxidize in air and possess significant sorption capacity relative to oxygen and moisture. At heating in air, reduction of porous condensate weight occurs right to the temperature of 650 °C, primarily, due to desorption of physically sorbed moisture. Final oxidation of Fe₃O₄ to Fe₂O₃ proceeds in the range of 380 °C–650 °C, due to the remaining fraction of physically adsorbed oxygen. At iron concentrations of up to 10–15 at%, condensate sorption capacity is markedly increased with increase of iron concentration, i.e. of the quantity of fine particles. Increase of condensation temperature is accompanied by increase of nanoparticle size, resulting in a considerable reduction of the total area of nanoparticle surface, and, hence of their sorption capacity. In addition to condensation temperature, the size and phase composition of nanoparticles can also be controlled by heat treatment of initial condensate, produced at low condensation temperatures. Magnetite nanoparticles can be transferred into stable colloid systems.

Carbon nanotube (CNT)/polymer composite materials can be high strength, stiff, and lightweight, which makes them attractive for fabrication of micromechanical structures. Here we demonstrate a method whereby smooth, thin, high CNT concentration composite sheets can be fabricated and patterned on the microscale using a process of photolithography and plasma etching. Two types of CNT/polymer composite sheets were fabricated: one made from CNTs grown on patterned supported catalyst and one made from CNTs grown with floating catalyst; these had thicknesses of 6 µm and 26 µm respectively and a roughness of less than 60 nm.

Solution deposition planarization (SDP) was used to modify the flexible metal substrates for high temperature superconductor (HTS) tapes to ensure an available and effective surface for subsequent growth of buffer films. The surface morphologies with different tape speeds and coating layers were systematically investigated. 16 layers SDP-films decreased the surface roughness (RMS) from 11.74 to 0.788 nm for Hastelloy C-276 and 12 layers SDP-films decreased the RMS from 20.93 to 0.903 nm for SUS 304. Follow-up study confirmed that the low value of RMS (<1 nm) and high reflectivity of SDP-films exhibit superior characteristics for ion beam-assisted deposited (IBAD)-MgO, sputtered LaMnO₃ films and YBCO films. A 10 m sample verified the stability of SDP-films on Hastelloy. The similar result for achieved SDP-films on SUS 304 (I_cAVG  =  110.1 A) and Hastelloy (I_cAVG  =  124.5 A) revealed the stainless steel has potential application value for coated conductor, which further reduced the cost of raw materials.

Oxygen adsorption and incorporation on the (1 0 0) surface of [0 0 1]-oriented GaN nanowires are investigated through first principle calculations. Results indicate that oxygen adsorption configurations are much more stable than oxygen incorporation. With increasing oxygen coverage, the surface of oxygen adsorption and incorporation become more stable and unstable, respectively. Besides, significant changes of surface structure occur after oxidization of the GaN nanowire surface, including changes in the thickness of the topmost bilayer and the distance between layers. Relaxation of the surface structure becomes more prominent with increasing oxygen coverage for adsorption cases. Compared with adsorption, the effects of incorporation on surface structures are more obvious. Furthermore, by comparison of band structures of clean surfaces and oxidized surfaces, both oxygen adsorption and incorporation will hinder the escape of photoelectrons due to the increase of the work function. Ultimately, calculations of Mulliken charge distribution and bond population suggest that oxygen impurities can obtain electrons from surface gallium and nitrogen atoms. The bond population of Ga–O for adsorption cases are larger than Ga–N, while that of incorporation cases is lower than Ga–N. All these calculations indicate that oxidization has significant impacts on the surface characteristics of GaN nanowires. Surface oxidization is harmful to the photoemission of optoelectronic devices fabricated by GaN nanowires. These results may contribute to the removal of surface oxides of GaN nanowires, but require further verification by experimental observation.

Epoxy resin matrix composites filled with dispersed micro and nano gadolinium oxide (Gd₂O₃) particles of different contents were fabricated in this study. The γ radiation shielding and mechanical properties of these micro and nano composites were evaluated by measuring mass attenuation coefficients at photon energies from 31 keV to 356 keV and flexural performances. Adding Gd₂O₃ obviously increases mass attenuation coefficients of composites, and the enhancement is stronger at low photon energy because of dominating photoelectric effect and k-edge of element gadolinium. Effect of Gd₂O₃ particle size on shielding property of composite was also discussed. The results show that nano-Gd₂O₃ composites have better ability to shield X and γ ray than micro-Gd₂O₃ composites, and an enhanced effect of ~28% is obtained with Gd₂O₃ content of around 5 wt.% at 59.5 keV. The reason is attributed to higher probability of interaction between γ-ray and nano particles. Especially, this effect is prominent in low particle concentration. For flexural property, nano-Gd₂O₃/epoxy composite show equivalent flexural strength and up to15% higher flexural modulus compared with micro-Gd₂O₃/epoxy composite. Based on these experimental results, nano-Gd₂O₃ reinforced epoxy composite is believed to be a promising novel radiation shielding material.

This study demonstrates the synthesis of a new class of peptide amphiphiles derived from aleuritic acid. The aleuritic acid was extracted and purified from the natural source shellac, which was later conjugated with tryptophan, leading to a new class of very short peptide amphiphiles. The self-assembling behavior of this compound was studied using spectroscopic and microscopic tools. This shellac-driven peptide was further used to cultivate gold nanoparticles (AuNPs) with the help of continuous wave (CW) laser light, where the AuNPs were encapsulated by peptide nanostructures. Laser irradiation caused nanoscopically confined heating in the AuNPs-peptide hybrid nanostructures. Such confined heating is mainly the result of scattering and simultaneous absorption of subwavelength power which is subjected to enhanced plasmonic resonances of the metal nanostructures. Hence, the generated heat power/photothermal effect of these AuNPs leads to disruption of the AuNP–peptide hybrids. Such light-induced prototype nano-structure hydrid devices have a wide range of thermal-plasmonic applications in the morphological modification of soft metal hybrid nanostructures for photothermal therapy and drug release.

We show that the properties of thin conductive inkjet printed lines of single-walled carbon nanotubes (SWCNT) can be greatly tuned, using only a few deposition parameters. The morphology, anisotropy and electrical resistivity of single-stroke printed lines are studied as a function of ink concentration and drop density. An original method based on coupled profilometry-Raman measurements is developed to determine the height, mass, orientational order and density profiles of SWCNT across the printed lines with a micrometric lateral resolution. Height profiles can be tuned from 'rail tracks' (twin parallel lines) to layers of homogeneous thickness by controlling nanotube concentration and drop density. In all samples, the nanotubes are strongly oriented parallel to the line axis at the edges of the lines, and the orientational order decreases continuously towards the center of the lines. The resistivity of 'rail tracks' is significantly larger than that of homogeneous deposits, likely because of large amounts of electrical dead-ends.

An Fe-MIL-88B/graphene oxide (GO) composite was successfully synthesized by the hydrofluoric acid (HF) free-solvothermal method. The sample was characterized by x-ray diffraction (XRD), N₂ adsorption–desorption Brunauer−Emmett−Teller (BET) method, transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), and x-ray photoelectron spectroscopy (XPS). BET shows that Fe-MIL-88B/GO is of a mesoporous structure, while XRD and XPS results reveal that besides the Fe-MIL-88B phase, a new α-FeOOH phase in the novel Fe-MIL-88B/GO composite is formed. The as-prepared Fe-MIL-88B/GO nanocomposite was used to test the photocatalytic degradation of reactive dye (reactive red-RR195) from aqueous solution. This novel metal-organic framework (MOF)/GO composite exhibited excellent photocatalytic activity. Thus, after 25 min of reaction under simulated sunlight irradiation, removal efficiency reached 98%. Moreover, this composite still maintained high photocatalytic activity after three cycles of reaction runs, indicating its high stability and reusability. This opens a new application potential for MOF/GO as a highly efficient photo-Fenton catalyst.

In this study, Monoclinic bismuth oxide nanorods (α-Bi₂O₃ NRs) were successfully synthesized by a simple one-step hydrothermal route using (water: ethanol) (1:1) as a mixed solvents at optimum conditions. The Bi₂O₃ nano-powder was characterized in detail by different techniques in terms of their structural, morphological, compositional, optical and photocatalytic properties. X-ray diffraction (XRD) analysis indicated that the as-synthesized Bi₂O₃ NRs exhibited high purity with monoclinic structure (α-Bi₂O₃) and good crystallinity. The Transmission electron microscope (TEM), Energy dispersive x-ray spectroscopy (EDXS) and Field Emission scanning electron microscope (FE-SEM) analysis clearly confirmed the high purity and the nanorod morphology of the as-synthesized Bi₂O₃ sample. The optical band gap of α-Bi₂O₃ NRs was estimated using the UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS) analysis according to the Kubelka–Munk theory. The optical band gap of α-Bi₂O₃ NRs was found to be 3.55 eV for an indirect allowed transition and 3.63 eV for a direct allowed transition. The Fourier transfer infrared spectroscopy (FTIR) was employed to check the structure as well as to evaluate the phonon vibration modes corresponding to Bi₂O₃. Photocatalytic activity of α-Bi₂O₃ NRs was investigated using UV source lamp. The as-synthesized α-Bi₂O₃ NRs photocatalyst exhibited better performance for degradation and decolorization of Methylene blue (MB) under ultraviolet (UV) irradiation. MB was completely photodegraded after 210 min under UV irradiation using α-Bi₂O₃ NRs as photocatalyst.

A versatile method to rapidly synthesize high quality gold nanorods through the use of a microwave terminated growth process is presented. Traditional nanorod growth procedures require lengthy growth periods in addition to the use of additional materials/steps to terminate growth, including extra reagents, precise control of reagent concentrations, and tuning of environmental factors such as temperature or pH. Utilizing brief, high power microwave irradiation exposure, one can improve the nanorod monodispersity and achieve a significant reduction in the level of nanoparticle impurities within the sub-30 min growth regime without the need of additional reagents or pH adjustments. In addition to the increased synthesis efficiency, microwave-terminated gold nanorods yielded an increase in the longitudinal:transverse plasmon peak ratios, signifying a reduction in nanoparticle impurities with samples treated at 24 min versus traditional 24 h growth procedures without microwave termination. Utilizing the microwave methodology also yields an improved homogeneity of the produced rods as shown with a narrower spectral full width at half maximum compared to traditionally grown gold nanorods.

Non-equilibrium molecular dynamics (NEMD) simulations is used to investigate the effect of support stiffness on thermal conductivity property based on the 'graphene-springs' model. It shows that the support stiffness greatly influences the thermal conductivity. Thermal conductivity of graphene decreases nonlinearly as the support stiffness increases. The temperature stability of thermal conductivity property of graphene can be improved by the support stiffness. For patterned stiffness supported stripe, thermal conductivity is significantly dependent on the patterned area, angle and stripe distribution. The work in this paper reveals the possibility for designing and controlling of thermal conduction of graphene by using support stiffness, which is beneficial to the application of graphene in nanoscale devices.

In this paper we discuss our recent microwave measurements on a graphene transistor fabricated on lithium niobate (LiNbO₃) substrates. Top gated graphene field-effect transistors (G-FETs) were fabricated on LiNbO₃ substrates and their high frequency operation were analyzed. The measured cutoff frequency f_T as a function of gate voltage derived from S parameters is found to be proportional to the G-FET's transconductance. An intrinsic cut off frequency up to 10 GHz was measured for a 600 nm gate graphene transistor.

This work is aimed at the formation of 2D and 3D superlattices (SL) of silver nanoparticles inside an emulsion droplet. The monodisperse nanoparticles required for SL formation were prepared by a digestive ripening technique. Digestive ripening is a post processing technique where polydisperse colloids are refluxed with excess surface-active ligands to prepare a monodisperse colloid. More uniform silver nanoparticles (~3.6  ±  0.5 nm) were formed by slow evaporation of organosols on a carbon-coated copper grid. The best 3D silver superlattices have been formed using an oil in water (o/w) emulsion method by aging the monodisperse particles in a confined environment like o/w emulsion at different temperatures ranging from 5 °C–4 °C. The kinetics of the formation of superlattices inside an emulsion droplet were investigated by controlling various parameters. The kinetics were found to be dependent on the emulsion aging period (30 d) and storage temperature of the emulsion (−4 °C).

A criterion of the energy efficiency of iron–boron–silicon metallic glasses in sulfuric acid solutions is proposed for the first time. The criterion has been derived based on calculating the limit of the ratio value of the conductivity of a metallic glass in aqueous solution to the conductivity of the metallic glass in air. In other words, the conductivity ratio of a metallic glass in aqueous solution to the conductivity of the metallic glass in air  = 1, was applied to determine the energy efficiency of the metallic glass in the aqueous solution when the conductivity of a metallic glass in air became equal (decreased) to the steady conductivity of the metallic glass in aqueous solution as a function of time of the exposure of the metallic glass to the aqueous solution. This criterion was not only used to determine the energy efficiency of different metallic glasses, but also, the criterion was used to determine the energy efficiency of metallic glasses exposed to a wide range of sulfuric acid concentrations. These conductivity values were determined by the electrochemical impedance spectroscopy (EIS). In addition, the criterion can be applied under diverse test conditions with a predetermined period of the operational life of the metallic glasses as functional materials. Furthermore, variations of the energy efficiency of the metallic glasses as a function of the acid concentration and time were produced by fitting the experimental data to a numerical model using a nonlinear regression method. The profiles of the metallic glasses exhibit a less conservative behavior of the energy efficiency than the proposed analytical criterion.

Network structure of SiO₂ and MgSiO₃ at 300 K and 3200 K is investigated by molecular dynamics simulation and visualization of simulation data. Structural organization of SiO₂ and MgSiO₃ is clarified via analysis the short range order (SRO) and intermediate range order (IRO). Network topology is determined via analyzing the bond between structural units, the cluster of structural units as well as spatial distribution of structural units. The polyamorphism as well as structural and dynamic heterogeneities are also discussed in this work.

The present paper reports the electrical properties of Ge₁Se_2.5 and Ge_0.6Se_2.5Sn_0.4 glasses at room as well as elevated temperatures. The samples were prepared using the melt quenching technique and the characterization was done using x-ray diffraction. The temperature dependence of the samples was studied through I–V characteristics and the data obtained were analyzed to obtain the dc electrical conductivity. The measurements were recorded in the temperature range 298–423 K on a Keithley electrometer. The results indicate that a thermally activated process is responsible for conduction in the temperature range 423–373 K, while in temperature range 373–298 K transport of charge carriers takes place via variable range hopping. Mott's 3D VRH model was applied to explain the hopping conduction occurring in these samples in the temperature range 373–298 K.

Sodium borosilicate glasses doped with lanthanum oxide were prepared using conventional melt quench technique. The XRD study of the glasses were carried out to affirm the amorphous nature of glass. The glass transition temperature T_g and crystallization temperature T_c were determined from the DTA. It is observed that T_g increases with the addition of La₂O₃. This increase in T_g is supported by density results.. The conductivity of the prepared glasses were studied using impedance analyzer in the frequency interval 20 MHz–2 mHz and in the wide temperature range 423 K–673 K. The obtained data has been correlated with various other parameters like density, molar volume and glass transition temperature. Modulus formalism is introduced to study relaxation behavior of these glasses. The overlapping of data on single master curve indicates that conduction mechanism in these glasses is compositional dependent and temperature independent. There is a good correlation between physical and electrical properties.

Fiber-reinforced composites using glass fiber and polyvinylchloride (PVC) have been used widely as architectural materials, electrical applications, automotive sector, and packing materials because of their reasonable price, chemical resistance, and dimensional stability. On the other hand, most of the composites are short fiber-reinforced PVC composites. In particular, in the case of fabric reinforced composites, undulated regions exist where there is only resin due to the characteristics of the weave construction, which causes a decrease in strength. In this paper, PVC was reinforced with chopped glass fibers with different lengths and contents to produce glass fiber fabric/PVC composites. The physical properties of the composites, such as thickness, density, volume fraction (V_f), and void content (V_c) were identified. The mechanical properties, including tensile strength, flexural strength, and interlaminar shear strength (ILSS) were also identified. A cross section of the composites was observed by scanning electron microscopy. Compared to the fabric reinforced composite without chopped glass fiber, the tensile strength was increased by 3.90% (from 316.15 MPa to 328.48 MPa at 5 wt.% chopped fibers with 3 mm length), flexural strength was increased by 7.15% (from 87.07 MPa to 93.30 MPa at 10 wt.% chopped fibers with 2 mm length), and ILSS was increased by 8.71% (from 7.34 MPa to 7.98 MPa at 10 wt.% chopped fibers with 1 mm length). Therefore, the critical fiber aspect ratio of chopped fiber works differently on each of the three mechanical properties.

The present study investigated multi-response optimization of certain input parameters viz. concentrations of oil and water repellent finish (Oleophobol CP-C^®), dimethylol dihydroxy ethylene urea based cross linking agent (Knittex FEL) and curing temperature on some mechanical, (i.e. tear and tensile strengths), functional (i.e., water contact angle 'WCA', oil contact angle 'OCA') and comfort (i.e. crease recovery angle 'CRA', air permeability 'AP', and stiffness) properties of an oleo-hydrophobic finished fabric under response surface methodology and the desirability function. The results have been examined using analysis of variance (ANOVA) and desirability function for the identification of optimum levels of input variables. The ANOVA was employed also to identify the percentage contribution of process factors. Under the optimized conditions, which were obtained with a total desirability value of 0.7769, the experimental values of Oleophobol CP-C^® (O-CPC), Knittex FEL (K-FEL) and curing temperature (C-Temp) agreed closely with the predicted values. The optimized process parameters for maximum WCA (135°), OCA (129°), AP (290 m s⁻¹), CRA (214°), tear (1492 gf) and tensile (764 N) strengths and minimum stiffness (3.2928 cm) were found to be: concentration of OCP-C as 44.44 g l⁻¹, concentration of cross linker K-FEL as 32.07 g l⁻¹ and C-Temp as 161.81 °C.

Here we report the results of compressive split Hopkinson pressure bar experiments (SHPB) conducted on unidirectional glass fibre reinforced polymer (GFRP) in the strain rate regime 5  ×  10²–1.3  ×  10³ s⁻¹. The maximum compressive strength of GFRP was found to increase by as much as 55% with increase in strain rate. However, the corresponding relative strain to failure response was measured to increase only marginally with increase in strain rates. Based on the experimental results and photomicrographs obtained from FE-SEM based post mortem examinations, the failure phenomena are suggested to be associated with increase in absorption of energy from low to high strain rates. Attempts have been made to explain these observations in terms of changes in deformation mechanisms primarily as a function of strain rates.

Core–shell fibers of polymethyl methacrylate (PMMA) and polystyrene (PS) have been successfully electrospun by coaxial electrospinning. To evaluate the influence of the solvent on the final fiber morphology, four types of organic solvents were used in the shell solution while the core solvent was preserved. Morphological observations with scanning electron microscopy, transmission electron microscopy and optical microscopy revealed that both core and shell solvent properties were involved in the final fiber morphology. To explain this involvement, alongside a discussion of the Bagley solubility graph of PS and PMMA, a novel criterion based on solvent physical properties was introduced. A theoretical model based on the momentum conservation principle was developed and applied for describing the dependence of the core and shell diameters to their solvent combinations. Different concentrations of core and shell were also investigated in the coaxial electrospinning of PMMA/PS. The core–shell fiber morphologies with different core and shell concentrations were compared with their single electrospun fibers.

Developing a advanced additive to promote the crystallization of poly(L-lactic acid) (PLLA) is still one of the main challenges for application. Here, magnesium phenylphosphonate (MgP), as a heterogeneous nucleating agent, was prepared to investigate directly its influence on the crystallization behavior and thermal stability of PLLA via a combination of differential scanning calorimetry (DSC), x-ray diffraction (XRD), and thermogravimetric analysis (TGA). The relevant results, from measurements of non-isothermal crystallization, the glass transition temperature, and XRD after melt crystallization, revealed that the MgP had excellent acceleration effectiveness in the melt crystallization of PLLA, and PLLA–0.7% MgP exhibited the sharpest non-isothermal crystallization peak and the highest non-isothermal crystallization enthalpy, suggesting that 0.7 wt% MgP is the optimal concentration in the PLLA matrix. In addition, these measurements also indicated that the incorporation of MgP could not change the crystal form of PLLA, and the non-isothermal crystallization behavior of PLLA–0.7% MgP did not have a significant relationship with the set final melting temperature. The melting behavior after non-isothermal crystallization further confirmed the crystallization-promoting effect of MgP for PLLA, and the second heating rate significantly affected the melting behavior of PLLA–MgP samples, resulting from the effect of heating rate on formation of crystallites. Thermal stability measurement showed that the addition of MgP could not change the thermal decomposition behavior of the primary PLLA, though MgP exhibited completely different thermal decomposition behavior. Furthermore, the influence of MgP concentration on the thermal decomposition temperatures of PLLA–MgP samples is negligible.

A capacitive sensor for 2,4-dichloro phenoxy acetic acid(2,4-D) determination in drinking water has been developed using molecularly imprinted polypyrrole on pencil graphite electrode (PGE). Molecular imprinted polymer (MIP) coated PGE was prepared by electropolymerization of pyrrole via chronopotentiometry in the presence of 2,4-D as the template molecule. The prepared electrodes were characterized by field emission gun-scanning electron microscopy, cyclic voltammetry, and electrochemical impedance spectroscopy (EIS). The capacitance change of MIP electrode was measured in the presence of 2,4-D using EIS. The developed capacitive sensor exhibited a linear range 0.06–1.25 µg l⁻¹ 2,4-D with limit of detection of 0.02 µg l⁻¹ and good selectivity towards 2,4-D in water with recovery from 92 to 110%. The results suggest the viable applicability of the MIP/PGE based sensor for the determination of the 2,4-D in water samples.

The interactions of block copolymers poly (ethylene oxide butylene oxide), E₅₈B₇ and E₅₈B₁₁ with anionic surfactant sodium dodecyl sulfate and cationic surfactant cetyltrimethylammonium bromide were studied by using different techniques such as surface tension, conductivity, and dynamic light scattering. The effect of salts in the Hofmeister series on polymer–surfactant systems was also investigated. The interactions were found to be dependent on both surfactant and polymer concentrations. The results were utilized to compute different thermodynamic parameters including enthalpy of micellization (ΔH_m), entropy of micellization (ΔS_m), free energy of adsorption (ΔG_ads) and free energy of micellization (ΔG_mic). For diblock-copolymer surfactant systems the negative value of (ΔG_mic) shows that the process of micelle formation is thermodynamically favorable. The solubilization in surfactant micelles altered the physicochemical properties of the block copolymer. The value of critical aggregation concentration decreases with the addition of Hofmeister anions, and the decrease is more pronounced for sodium fluoride as compared to sodium iodide.

The exploration of new and advanced electrode materials are required in electronic and electrical devices for power storage applications. Also, there has been a continuous endeavour to formulate strategies for extraction of high performance electrode materials from naturally obtained waste products. In this work, we have developed an in situ hybrid nanocomposite from coffee waste extracted porous graphene oxide (CEPG), polyaniline (PANI) and silver nanoparticles (Ag) and have found this novel composite to serve as an efficient electrode material for batteries. The successful interaction among the three phases of the nano-composite i.e. CEPG–PANI–Ag have been thoroughly understood through RAMAN, Fourier transform infrared and x-ray diffraction spectroscopy, morphological studies through field emission scanning electron microscope and transmission electron microscope. Thermo-gravimetric analysis of the nano-composite demonstrates higher thermal stability up-to a temperature of 495 °C. Further BET studies through nitrogen adsorption–desorption isotherms confirm the presence of micro/meso and macro-pores in the nanocomposite sample. The cyclic-voltammetry (CV) analysis performed on CEPG–PANI–Ag nanocomposite exhibits a purely faradic behaviour using nickel foam as a current collector thus suggests the prepared nanocomposite as a battery electrode material. The nanocomposite reports a maximum specific capacity of 1428 C g⁻¹ and excellent cyclic stability up-to 5000 cycles.

Kaolinite (KLN) was successfully decorated by polyacrylic acid (PAA) brushes via a facile 'one-step' manner in this study. This process was achieved by heterogeneous esterification between carboxyl on the PAA chains and hydroxyl on the KLN in the presence of Al³⁺ as catalyst. The prepared composite (denoted as PAA-g-KLN) was characterized by Fourier transform infrared spectroscopy (FTIR), x-ray diffraction pattern (XRD), Field emission scanning electron microscopy (FE-SEM) and thermogravimetry (TG) to confirm the successful grafting of PAA brushes on the surface of KLN. Subsequently, the PAA-g-KLN was used as adsorbent for the removal of Cu²⁺ from wastewater. Due to the introduction of abundant and highly accessible carboxyl groups on the surface of kaolinite, PAA-g-KLN exhibited an enhanced adsorption performance than raw kaolinite, which could be up to 32.45 mg·g⁻¹ at 45 °C with a fast adsorption kinetic. Theoretical models analysis revealed that Langmuir isotherm model and the pseudo second-order model were more suitable for well elucidation of the experimental data. In addition, the regeneration experiment showed that the PAA-g-KLN could still keep a satisfactory adsorption capacity (>65%) by being reused for 6 consecutive cycles. The study provides an easy and rapid method for surface polyelectrolyte modification on inorganic mineral as a promising adsorbent to remove Cu²⁺ from aqueous solution.

A.cepa peels are obtained from mature onion bulbs. Because of the continuous need for energy, alternative avenues for producing energy are gaining importance. The motivation for this work is based on an urgent need to source energy from readily available waste materials like domestic onion peels. Dye sensitized solar cells (DSSCs) fabricated via doctor blade method and high temperature sintering from waste (onion peels) are investigated for their ability to convert solar to electrical energy. The charge carriers were revealed under phytochemical screening. Functional groups of compounds present in A.cepa peel were analyzed with Fourier transform in infrared (FTIR). The influence of different electrolyte sensitizer is observed on the DSSCs under standard air mass conditions of 1.5 AM. The microstructure properties of these A.cepa DSSCs were explored using scanning electron microscope with energy dispersive spectroscopy (SEM/EDS), x-ray diffraction and Fluorecence spectroscopy (XRF). The interfacial boundary between A.cepa dye, TiO₂ framework of TiO₂ and indium doped tin oxide (ITO) reveals several prominent anatase and rutile peaks. Photoelectric results, revealed dye-sensitized solar cells with a maximum power output of 126 W and incident photon to conversion energy (IPCE) of 0.13%.This work has established that A.cepa peels can be used as a source of micro-energy generation.

Ordered microporous Y zeolite was successfully synthesized by hydrothermal treatment using metakaolin and Ludox (40% SiO₂) as an aluminum and silica source respectively. The metakaolin was obtained by thermal treatment of Algerian kaolin. The obtained Y zeolite was exchanged by different cations such as Cu²⁺, Ni²⁺, Ca²⁺, Na⁺ and used for the CO₂ adsorption at 0 °C. The structural features of the materials were determined by various physico-chemical techniques such as x-ray diffraction, nitrogen sorption at 77 K, Fourier transform infrared spectroscopy and scanning electronic microscopy. The CO₂ adsorption at 0 °C was carried using a volumetric method. The adsorption isotherms of CO₂ exhibit nonlinear concave curves and showed a high adsorption capacity for CO₂ from the M-Y zeolites. The equilibrium CO₂ adsorption capacity increase in the following order of Cu²⁺  <  Ni²⁺  <  Ca²⁺  <  Na⁺. The experimental isotherm data of the CO₂ adsorption was best described by the Langmuir model giving a maximum adsorbed amount q_m  =  77.57 cm³ · g⁻¹ STP for Na-Y zeolite.

The influence of a magnetic field on electrical conductivity and the third-order nonlinear optical properties exhibited by carbon nanotubes decorated with platinum nanoparticles is reported. The experimental and numerical results of the nonlinear magneto-optics, magneto-conductivity and photo-thermal processes were analyzed. The simultaneous impact of optical absorptive nonlinearities and the magnetic field in the sample allowed us to encrypt information in the electronic signals by designing an exclusive-OR logic gate scheme. The samples were prepared in film form using a spray pyrolysis route and a chemical vapor deposition approach. The characterization of the morphological nature of the multiwall nanotubes was evaluated by transmission electron microscopy and x-ray techniques. A vectorial two-wave mixing method was conducted by using nanosecond pulses at 532 nm in order to estimate the nonlinear optical behavior in the nanohybrid materials explored. An important enhancement in the phonon-band-structured transport from the inclusion of nanoparticles in the nanotubes was numerically calculated. A distinguished modification in the transient dynamics of the photo-thermal transitions and Kerr nonlinearities was pointed out to be due to the metallic nanoparticles incorporated in the sample. An extraordinary evolution of the magneto-conductivity, together with a strong change in the optical Kerr transmittance exposed to the magnetic field in propagation through the nanostructures, was observed.

Graphene has lots of attractive properties. However, most of its optimal properties are only associated with individual sheets. Producing a colloidal form of graphene can effectively avoid graphene aggregation and thus maintain its original performance. In this paper, an electrolytic method was utilized to prepare graphene colloids. Initially, graphene oxide (GO) was produced from graphite by a pressurized oxidation method. The high concentration of H⁺ or OH⁻ was found to facilitate the aggregation of GO. Then, GO was reduced by nascent hydrogen, which was generated by reducing hydrogen ions on an iron cathode in the electrolytic method. X-ray diffraction, Raman spectrum, thermogravimetric analysis and x-ray photoelectron spectroscopy analyses indicated that the nascent hydrogen can effectively reduce GO to graphene. Atomic force microscopy analysis and dispersibility evaluation of graphene colloids proved that the novel electrolytic method can prepare well-dispersed single-layer graphene colloids.

This work reports a simple, versatile and facile one-step process to prepare the three-dimensional (3D) N-doped noncovalent functionalization polystyrene/reduced graphene oxide (PS/rGO) composites. In this, N, N-dimethylformamide (DMF) acts as the solvent, reducing agent, and more importantly, the N-doping agent. Various measurements have been carried out to characterize the structure and morphology of PS/rGO composites, in particular for the excellent electrical conductivity of PS/rGO composites compared with virgin PS, which was attributed to the 3D pores structure and the N-doping. With regards to the unique properties of graphene, the 3D framework structure and the N-doping, this composite material has great potential properties such as electro-magnetic interference shielding effectiveness (EMI) to be explored.

Impedance matching and microwave attenuation play key roles in electromagnetic absorption. Moderate electromagnetic parameters will lead to matched impedance matching and attenuation ability. Using magnetic/dielectric composites is considered to be an efficient strategy for achieving excellent electromagnetic absorbing properties. The Co@C reported in this research not only resulted in improved impedance matching behavior, but also possessed strong microwave attenuation ability due to its polarizing and conducting features. As a result, the effective absorption frequency of the optimal absorber covers 4.2 GHz under a thin coating layer of 1.4 mm. The attenuation mechanism has also been discussed in depth in this study.

Liquid-phase-exfoliated, pristine graphene nanosheets (GNSs) are dispersed in thermoplastic polyurethane (TPU) to obtain free-standing conducting composite films. The composites are tested for electromagnetic interference (EMI) shielding applications in the X-band (8–12 GHz). A constant increase in the electromagnetic attenuation is observed as a function of GNS loading (0–0.12 V_f). The EMI shielding effectiveness of about 1 dB for the neat polymer is enhanced to about 14 dB at 0.12 V_f GNS as the electromagnetic energy is dissipated due to the GNS conducting network formed inside. Conducting behavior of GNS–TPU composites is confirmed by electrical conductivity measurements along with cyclic voltammetry as the band gap is reduced with a graphene increment. Scanning electron microscopy predicts a homogeneous dispersion of GNS inside composites. For such thin composite films (0.03–0.05 mm), the EMI shielding effectiveness is considerable.

In this research, the potential of chitosan/Fe₃O₄/graphene oxide (CS/Fe₃O₄/GO) nanocomposite for efficient removal of methylene blue (MB) as a cationic dye from aqueous solutions was investigated. For this purpose, first, graphene oxide (GO) was prepared from pencil's graphite by Hummer's method, then after, CS/Fe₃O₄/GO was synthesized via chemical co-precipitation method from a mixture solution of GO, Fe³⁺, Fe²⁺ and chitosan. The synthesized CS/Fe₃O₄/GO was characterized by XRD, VSM and SEM techniques. Also, the various parameters affecting dye removal were investigated. Dye adsorption equilibrium data were fitted well to the Langmuir isotherm rather than Freundlich isotherm. The maximum monolayer capacity (q_max), was calculated from the Langmuir as 30.10 mg · g⁻¹. The results show that, CS/Fe₃O₄/GO nanocomposite, can be used as a cheap and efficient adsorbent for removal of cationic dyes from aqueous solutions.

The mechanical performance of superelastic NiTi with various grain sizes (GSs) in nanocrystalline regime (GS  <  30 nm) are investigated. With the help of digital image correlation, both global and local mechanical responses of NiTi during quasi-static test and fatigue cycling are recorded. If GS is below 14 nm, NiTi deforms homogenously; if GS is above 14 nm, NiTi deforms in a heterogeneous manner. The mechanical response, the fatigue life, the dissipation energy and the resistance to the dissipation energy degradation of nanostructured NiTi are addressed and analyzed. The results indicate that the mechanical performance of NiTi can be designed and optimized by controlling GS in a moderate regime.

This work focuses on using isoelectronic substitution to modify electronic density of states (DOS) of bismuth (Bi) compounds for thermoelectric property modification. The calculations include first-principle density functional theory (DFT) and analytical calculations based on Mott formula. The thermoelectric materials selected in the present study are Bi compounds, i.e. Bi₂Te₃, Bi₂Se₃, Bi₂Se₂Te, Bi₂Te₂Se, Bi₂O₂Te, and Bi₂O₂Se. The results reveal that isoelectronic substitution of Se and Te atoms with O atoms (Bi₂O₂Te and Bi₂O₂Se) introduces changes in DOS around the valence band maximum and the conduction band minimum, exhibiting the figure of merit (ZT) approaching the values 0.004 and 0.03 at room temperature, for Bi₂O₂Se and Bi₂O₂Te, respectively. Though the ZT of these oxide compounds are inferior to conventional thermoelectric materials, it is known that they show better stability and less toxicity which could be the alternative materials.

Structural, electronic and optical properties of pure and Ga doped ZnO (GZO), with different concentrations (x  =  6.25%, 12.5% and 25%) are investigated by the ab initio full-potential linearized augmented plane wave (FP-LAPW) method, using the exchange and correlation potential within the generalized gradient approximation and the modified Becke–Johnson (mBJ) exchange potential. In the present work, some electronic properties, such as the band structure and the density of states as well as some optical properties, such as the dielectric function ε(ω), the refractive index n(ω), the reflectivity R(ω) and the electron energy-loss L(ω) were improved. The calculated lattice constants and the optical band gap (3.27 eV) of pure ZnO were found to be in good agreement with the experimental results. We have shown that the increase of the Ga concentration in ZnO creates shallow donor states Ga-4s in the minimum of the conduction band around the Fermi level, increasing the optical band gap and the conductivity. The absorption edge, presents in the imaginary part of the dielectric function, moves to higher energy levels with increasing Ga concentration. The static refractive index and the reflectivity of GZO increased with the increasing Ga concentrations. The L(ω) spectrum shows a single metal property for pure ZnO, and two peaks were observed for GZO, a small one around 2 eV originated from Ga doping and a second moved to higher energies indicating that the metallic character is more present in GZO than in pure ZnO.

We have reported photo catalytic properties of bismuth selenide (Bi₂Se₃) and nickel doped (5 mol%) bismuth selenide (Bi₂Se₃) samples on two different dyes, congo red (CR) and rose bengal (RB) under visible-light irradiation without and with hydrogen peroxide. A maximum rate constant of 0.0365 min⁻¹ for RB dye has been observed for the nickel doped bismuth selenide catalyst in presence of hydrogen peroxide. A possible mechanism for improvement of photo catalytic performance has been explained based on band structure.

Formation energies, electronic and optical properties of pure ZnO, and Er-doped ZnO with and without incorporating the intrinsic point defects (IPDs) were studied by the first-principles method based on density functional theory. The results indicated that stable Er-doped ZnO compound can only exist under Zn-poor and Er-rich conditions. Quite interestingly, doping Er into the ZnO lattice can inherently inhibit the donor-type IPDs in ZnO and favor the formation of acceptor-type IPDs, which might suggest a possibly facile way to suppress the self-compensation induced by the donor-type IPDs and achieve stable p-type ZnO by Er doping. More absorption peaks appeared in the visible and infrared regions, and a new absorption edge near ~0 eV was observed when the acceptor-type IPDs were incorporated. The strong interactions between the Er dopants and the IPDs in the optical properties, as confirmed from the results of density of states, were considered to be one of the important reasons for the strong light absorptions in both the visible and infrared regions.

We examine high quality, single crystal CdTe epilayer grown by molecular beam epitaxy (MBE) on ($2\,1\,1$)B GaAs substrate using both positions and full width at half maximums (FWHMs) of reciprocal lattice points (RLPs). Our results demonstrate that reciprocal space mapping (RSM) is an effective way to study the structural characteristics of the high-index oriented epitaxial thin films having a large lattice mismatch with the substrate. The measurement method is defined first, and then the influence of shear strain (${{\epsilon}_{xz}}$) on the position of the ($5\,1\,1$) node of epilayer is clarified. It is concluded that the lattice tilting is likely to be related with the lattice mismatch. Nondestructive measurement of the dislocation density is achieved by applying the mosaic crystal model. The screw dislocation density, estimated to be $7.56\times {{10}^{7}}$ cm⁻², was calculated utilizing the broadened peakwidths of the asymmetric RLP of the epilayer lattice.

In this paper, we report a facile growth of freestanding PbI_2−xCl_x film and microbulk via hydrothermal method without additives. The properties of samples were systematically investigated by field emission scanning electron microscopy, x-ray diffraction and UV–vis diffuse reflection spectroscopy. The results reveal that there appears to be two types of morphological PbI_2−xCl_x due to the anisotropy in the effective surface energy, and the underlying growth mechanism behind the observation is also discussed. This new approach is promising for the fabrication of PbI_2−xCl_x precursor material of detectors and solar cells.

In the current work, ferrofluids belonging to the series Co_xFe_1−xFe₂O₄ with Co concentration (x  =  0–0.8) are synthesized by chemical co-precipitation technique. Structural, magnetic and optical properties of these ferrofluids have been investigated. The XRD results confirm the single phase cubic spinal structure belonging to the space group (Fd3m). The samples exhibit polycrystallinity with almost negligible impurities. Analyses of TEM demonstrate size distribution of the prepared nanoparticles in the range of 6–11 nm that are almost spherical in shape. Optical absorption spectra depict band edges of the samples ranging from 3 to 3.7 eV which is attributed by finite quantum confinement effect. Magnetic response of the ferrofluids at room temperature probed through VSM studies reveals that substituting cobalt for iron in magnetite change coercivity from 123 Oe (ferromagnetic) to 0 (superparamagnetic) states. The saturation magnetization and remanence are found to increase upto x  =  0.4 and then significantly decreases for x  =  0.6–0.8 arising due to effects of exchange interaction between the tetrahedral and octahedral sub lattices. Magnetic control of the optical properties for different concentrations is achieved in these fluids.

To investigate the optoelectronics properties of Cs/NF₃ adsorption on GaN (0 0 1) photocathode surface, different adsorption models of Cs-only, Cs/O, Cs/NF₃ adsorption on GaN clean surface were established, respectively. Atomic structures, work function, adsorption energy, E-Mulliken charge distribution, density of states and optical properties of all these adsorption systems were calculated using first principles. Compared with Cs/O co-adsorption, Cs/NF₃ co-adsorption show better stability and more decline of work function, which is more beneficial for photoemission efficiency. Besides, surface band structures of Cs/NF₃ co-adsorption system exhibit metal properties, implying good conductivity. Meanwhile, near valence band minimum of Cs/NF₃ co-adsorption system, more acceptor levels emerges to form a p-type emission surface, which is conductive to the escape of photoelectrons. In addition, imaginary part of dielectric function curve and absorption curve of Cs/NF₃ co-adsorption system both move towards lower energy side. This work can direct the optimization of activation process of NEA GaN photocathode.

To investigate the effects of local bond relaxations on the electronic and photocatalysis performances of MoS₂ photocatalyst, the thermodynamic, electronic and optical performances of nonmetal doped 3R–MoS₂ have been calculated using density functional theory. Results shown that the positive or negative charges of impurity ions are decided by the Pauling electronegativity differences between Mo (or S) and nonmetal atoms, the H, B, Si, Cl, Br and I ions priority to occupy the interstitial site and the other ones tend to occupy the substitutional site. The localized electrons around NM ions are caused by the relaxed Mo–NM and S1–NM bonds, which can effectively affect the electronic and photocatalytic performances of specimens. The optical performances have been altered by the slightest changes of band gap and the newly formed impurity levels; the active sites have been also changed based on the different distributions of the highest occupied molecular orbital and the lowest unoccupied molecular orbital. In brief, the B, N, F, Si, P, Cl, As, Se, Te and Br ions contribute to the separation of photogenerated e⁻/h⁺ pairs and enhance the photocatalysis efficiency, but the H, C, O, and I ions will become the recombination centers of photogenerated e⁻/h⁺ pairs and should be avoided adding into 3R–MoS₂.

Annealing effect of granular ZnO has been studied by Doppler broadened electron positron annihilated γ-ray (0.511 MeV) line shape measurement. Ratio curve analysis shows that granular ZnO samples contain both Zn and O vacancies. Such defects exist as agglomerates of several vacancies and start to recover above 400 °C annealing. It has also been observed that due to annealing temperature difference of 125 °C (from 325 °C to 450 °C), huge change occurs in low temperature photoluminescence (PL) of ZnO. Significant reduction of free to bound (FB) transition ~3.315 eV is observed for increasing the annealing temperature. It has been conjectured that ~3.315 eV PL in ZnO is related to particular decoration (unknown) of both Zn and O vacancies. The methodology of revealing defect-property correlation as employed here can also be applied to other types of semiconductors.

The YBa₂Cu₃O_7−x (YBCO) superconducting film of 70 nm thickness was prepared on a LaAlO₃ (LAO) substrate via the sol–gel method, following which the Pb(Zr_0.52Ti_0.48)O₃ (PZT) ferroelectric film possessing interfacial coherent structure was grown via pulsed laser deposition (PLD) method, and then the Pt top electrode was deposited onto the PZT film by DC sputtering, resulting in the Pt/PZT/YBCO tri-layer structure. The ferroelectric hysteresis characteristics and the effects of ferroelectric polarization field of PZT on the electrical properties and magnetization of YBCO were studied for the temperature range of 50–300 K. Results reveal that as the temperature decreases, the remanent polarization of Pt/PZT/YBCO remains nearly constant, while the coercive field increased. The R–T curve of YBCO shifts upwards (positive polarization) or downwards (negative polarization) due to the influence of PZT polarization, indicating that the ferroelectric polarization of PZT modulates the R–T curve of YBCO. When YBCO is in the superconducting state, the magnetization of YBCO decreases with increasing polarization of PZT, indicating that the polarization field of PZT has a modulation effect on the magnetization of YBCO. Further investigation on the J–V curve of Pt/PZT/YBCO revealed a threshold conduction voltage (V_t) and when the applied bias voltage was lower than V_t, the leakage current of Pt/PZT/YBCO was small, and when the applied voltage was higher than V_t, the leakage current rapidly increased. Meanwhile, the V_t increased with decreasing temperature and then markedly changes at the superconducting transition temperature of YBCO.

The perovskite manganite families Gd_1−xCa_xMnO₃ and Nd_1−xCa_xMnO₃, where $0\leqslant x\leqslant 1$ (hereafter GCMO and NCMO, respectively) were screened for the prospect of a strong magnetocaloric effect by experimentally determining magnetic transition entropies. Magnetic transitions in the temperature range of 5–400 K were investigated in external fields up to 5 T. Entropy-based refrigerant capacities and magnetic hysteresis losses were also taken into account. The evolution of the magnetocaloric performance estimates versus the Ca concentration, x, was found to be qualitatively identical to that reported in Pr_1−xCa_xMnO₃ (PCMO). In line with this analogy, the highest estimated magnetocaloric performance of GCMO and NCMO was found in the low-x region, below the temperature of 140 K. Here the entropy-based figures of merit were comparable to the best magnetocaloric transitions seen in e.g. PCMO and Gd₅Si₂Ge₂. The low magnetic hysteresis, dielectricity and tunability by forming solid solutions with other manganites add to the potential of GCMO and NCMO as low-temperature magnetic refrigerants. At higher temperatures their magnetocaloric applicability is very limited at best, but a side-by-side comparison of GCMO, NCMO and PCMO can also be seen as a valuable theoretical instrument for understanding the general magnetic phase diagram of low bandwidth manganites.

We report the magnetic properties of compounds in the KBaRE(BO₃)₂ family (RE  =  Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb), materials with a planar triangular lattice composed of rare earth ions. The samples were analyzed by x-ray diffraction and crystallize in the space group R-3m. Physical property measurements indicate the compounds display predominantly antiferromagnetic interactions between spins without any signs of magnetic ordering above 1.8 K. The ideal 2D rare earth triangular layers in this structure type make it a potential model system for investigating magnetic frustration in rare-earth-based materials.

We report that Fe₃GeTe₂ can form a wide solid solution by substitution of As for Ge, providing an opportunity to tune the magnetic and electronic properties in this 2D material. The crystal structure, physical properties and electronic structure of iron-deficient solid solution Fe_3−yGe_1−xAs_xTe₂ (0  ⩽  x  ⩽  0.85) are studied. We found that the Curie temperature can substantially change from 177 K to 33 K and resistivity decreases by about 30% with the arsenic doping x from 0 to 0.85. First principles calculations demonstrate that the elongation of Fe(1)–Fe(1) dumb-bells along c axis is essentially responsible for decreasing the integrated spin density of states below Fermi level and weakening spin polarization, resulting in a decrease of Curie temperature. Our study reveals the magnetism manipulation can be realized via modification of bondlengths in 2D magnetic materials.

The present investigation shows the significant improvement in the structural, magnetic and dielectric properties of Bi_1−xCe_xFe_1−xCo_xO₃ (x  =  0, 0.01, 0.03, 0.05) multiferroic materials, synthesized via an auto-combustion method. The synthesized materials are found to have structural distortion in the rhombohedral R3c structure as observed by x-ray diffraction. The high dielectric constant (~1850 at 2.5 MHz) was found for x  =  0.05 multiferroic material from dielectric analysis. The presence of a weak doublet along with a sextet pattern in the Mossbauer spectra indicates the secondary phase. M–H loops of these materials demonstrate that Ce–Co doping in BiFeO₃ enhances retentivity, coercivity, and saturation magnetization. Improvement in the magnetic and dielectric properties in Ce–Co doped BiFeO₃ leads to multifunctional device application.

In this study, ball-milling method was adopted for the synthesis BaM-hexaferrites BaFe_12−2xCu_xMn_xO₁₉ (x  =  0.00, 0.25, 0.50, 0.75, and 1.00). The system shows pure BaM phase in the samples with x  =  0.0 and x  =  0.25. At higher substituent concentrations, Y-type hexaferrite phase developed. The evolution of the Y-type phase was confirmed by Rietveld refinement of the x-ray diffraction patterns, and the thermomagnetic measurements from which the Curie temperature of the existing phases was determined. The Curie temperature for the M-type phase decreased with increasing x, signaling the reduction of the superexchange interaction strength. The particle size of the pure sample was within the critical single-domain size, and the size increased with increasing x as determined by SEM imaging. These variations induced significant reduction in the coercivity as a consequence of the development of multi-domain particles with increasing x. The coercivity decreased from 3.4 kOe for the pure sample, down to 50 Oe for the sample with x  =  0.50, and then increased slightly at higher x values. The saturation magnetization (M_s) decreased monotonically with increasing x, from 67.2 (emu g⁻¹) for pure sample, down to 43.0 emu g⁻¹ for the sample with x  =  1.0. The sample with x  =  0.25 exhibited magnetic properties suitable for high density magnetic recording, while the samples with higher x values exhibited magnetic softening, prohibiting the potential for such applications.

The mechanical, electronic and optical properties of KH under high pressure have been studied using the generalized gradient approximation and Heyd-Scuseria-Ernzerh of hybrid method within density functional theory. Based on the usual condition of equal enthalpies, high pressure phase transition of KH from B₁ to B₂ was confirmed, is about 4.1 GPa, and normalized volume collapse ΔV_P/V₀ is about 11.09%. The calculated equilibrium structural parameters and elastic modulus are in excellent agreement with the experimental and other theoretical results. At ground states, B₁ KH is elastic stable, but B₂ KH is unstable. C₁₁ and c' are the main factors, which cause the structural phase transition under the pressures. The band structures and density of states of KH were calculated and analyzed in detail. Valance bands are local and conduction bands are continuous. The VBs mainly originate from K 3s, 3p and H 1s states, and the CBs consist of K 3s, 3p states, some hybridized levels are found between K 3s and 3p states. Mulliken population analysis of KH indicate that the charge populations of H 1s and K 3p states are very obvious but K 3s states are relatively weak, the charge transfers are from K to H. The linear response optical properties of KH were emphatically predicted combing with the band structures and frequency-dependent and dielectric function ε(ω).

A single crystal of bis-thiourea nickel nitrate (BTNN) doped potassium dihydrogen phosphate (KDP) has been grown from solution at room temperature by a slow evaporation technique. The cell parameters of the grown crystals were determined using single crystal x-ray diffraction analysis. The different functional groups of the grown crystal were confirmed using Fourier transform infrared analysis. The improved optical parameters of the grown crystal have been evaluated in the range of 200–900 nm using UV–visible spectral analysis. The grown crystal was transparent in the entire visible region and the band gap value was found to be 4.96 eV. The influence of BTNN on the third order nonlinear optical properties of KDP crystal has been investigated by means of the Z-scan technique. The second harmonic generation (SHG) efficiency of grown crystal measured using a Nd-YAG laser is 1.98 times higher than that of pure KDP. The third order nonlinear optical susceptibility (χ³) and nonlinear absorption coefficient (β) of BTNN doped KDP crystal is found to be 1.77  ×  10⁻⁵ esu and 5.57  ×  10⁻⁶ cm W⁻¹ respectively. The laser damage threshold (LDT) energy for the grown crystal has been measured by using a Q-switched Nd:YAG laser source. The bis-thiourea nickel nitrate shows authoritative impact on the dielectric properties of doped crystal. The influence of bis-thiourea nickel nitrate on the mechanical behavior of KDP crystal has been investigated using Vickers microhardness intender. The thermal behavior of BTNN doped KDP crystal has been analyzed by TGA/DTA analysis.

As-grown and annealed undoped n type InAs single crystals have been studied by Hall effect measurement, infrared transmission (IR) spectroscopy, photoluminescence spectroscopy (PL) and glow discharge mass spectroscopy (GDMS). After annealing, below-gap infrared transmittance of the InAs single crystal increases significantly with the annihilation of a 0.383 eV PL peak related defect. Mechanism of the transmission enhancement and the attribution of the defect is discussed based on the experimental results.

Electron paramagnetic resonance (EPR) spectra and their angular dependencies were measured for Co²⁺ trace impurities in stoichiometric samples of lithium niobate doped with rhodium. It was found that Co²⁺ substitutes for Li⁺ in the dominant axial center (Co_Li) and that the principal substitution mechanism in stoichiometric lithium niobate is 4Co²⁺ ↔ 3Li⁺  +  Nb⁵⁺. The four Co²⁺ ions can occupy the nearest possible cation sites by occupying a Nb site and its three nearest-neighbor Li sites, creating a trigonal pyramid with C₃ symmetry, as well as non-neighboring sites (e.g. a Co_Nb–Co_Li pair at the nearest sites on the C₃ axis with two nearby isolated single Co²⁺ ions substituted for Li⁺). In congruent crystals and samples with Li content enriched by vapor transport equilibrium treatment the excess charge of the Co²⁺ centers is compensated by lithium vacancies located rather far from the Co²⁺ ions for the dominant axial center or in the nearest neighborhood for low-symmetry satellite centers (the Co²⁺ ↔ 2Li⁺ substitution mechanism). The use of exact numerical diagonalization of the spin-Hamiltonian matrices explains all the details of the EPR spectra and gives a value for hyperfine interaction A_|| that is several times smaller than that obtained using perturbation formulae. The refined values of A and g-tensor components can be used as reliable cornerstones for ab initio and cluster calculations.

In this work, we report on sol–gel synthesis and photoluminescence of SiO₂–Si:Er³⁺ nanocomoposite films. The films were characterized by x-ray diffraction, field emission scanning electron microscope and photoluminescence measurements. We demonstrate that the incorporation of Si nanocrystals with sizes of 10–20 nm into the silica matrix resulted in strong Er-related PL in the infrared region peaking at 1535 nm and that the film can be well excited by non-resonant wavelengths (250–260 nm). The role of Si nanocrystals as sensitizers and the dependence of the Er-related PL on Er-doping concentration and annealing temperature are also discussed.

The present discrepancy among the theoretical electronic structures of anatase TiO₂ has been investigated by using first-principles calculations. This glaring disagreement among the theoretical electronic structures of anatase has been resolved by choosing proper unit cells and corresponding high-symmetry k-points. It is confirmed that anatase is an indirect band-gap material and any deviations, such as a change from indirect to direct which was reported earlier in the conventional cell, results when the equilibrium lattice parameters are modified and the structure is distorted. In the primitive cell scenario, the valence-band maximum gets modified when the equilibrium lattice parameters are changed, but the band gap stays indirect.

Based on density functional theory, the structural, electronic and optical properties of α-, β-, γ-, δ- and ε-BeH₂ have been investigated using the plane-wave pseudo-potential and Broyden–Fletcher–Goldfarb–Shanno approaches. The calculated equilibrium structural parameters are in excellent agreement with the experimental and other theoretical results. The mechanical stabilities of BeH₂ were determined by phonon spectrum calculation, indicating that α-, γ-, δ- and ε-BeH₂ are dynamically stable, but β-BeH₂ is dynamically unstable. The band structures and density of states of BeH₂ were calculated and analyzed in detail. Four common characteristics of the valence bands and conduction bands for BeH₂ were described. The α- and β-BeH₂ exhibit direct band gap characteristics, and the γ-, δ- and ε-BeH₂ are indirect band gaps. Mulliken population analysis of BeH₂ indicates that the charge populations of H 1s and Be 2p states are very obvious, but Be 2s states are relatively weak; the charge transfers are from Be–H, and all of the BeH₂ are mixture bonding materials (covalent + ionic bond) and the covalent character is obvious. By combining the electronic properties and frequency-dependent dielectric function ε(ω), the linear response optical properties of BeH₂ were predicted with a photoelectron energy up to 30 eV.

We present a detailed study of correlation- and pressure-induced electronic reconstruction in hexagonal iron monosulfide, a system which is widely found in meteorites and one of the components of Earth's core. Based on a perusal of experimental data, we stress the importance of multi-orbital electron-electron interactions in concert with first-principles band structure calculations for a consistent understanding of its intrinsic Mott–Hubbard insulating state. We explain the anomalous nature of pressure-induced insulator-metal-insulator transition seen in experiment, showing that it is driven by dynamical spectral weight transfer in response to changes in the crystal-field splittings under pressure. As a byproduct of this analysis, we confirm that the electronic transitions observed in pristine FeS at moderated pressures are triggered by changes in the spin state which causes orbital-selective Kondo quasiparticle electronic reconstruction at low energies.

Recently, the preparation of flexible graphene-based micro-supercapacitors has attracted considerable attention. In this paper, a flexible and all-solid-state micro-supercapacitor was fabricated by LightScribe technology. Additionally, the influences of the drop-cast amount of graphene oxide (GO) and the numbers of LightScribe times on the performance of the supercapacitor were systematically investigated by means of cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge/discharge. It was determined that the electrochemical performance of the micro-supercapacitor was optimal when the drop-cast amount was 0.38 mg cm⁻². Moreover, a positive correlation was found between the capacitance and the number of LightScribe times. The maximum capacitance was 2.9 mF cm⁻², which was reached with 20 rounds of LightScribe.

The paper presents a technological solution for high frequency packaging platform evaluated up to 40 GHz. The main purpose of this development was to define an alternative hybrid technology that is more flexible and faster to prototype compared with thin film or multi chip module (MCM-D). The alternative technology also shows adequate performance for high bit rate solutions integrating optical and electronics blocks. This approach consists of a soft substrate (laminate material), plating processes (electroless Ni–P/Au, electrolytic Au) and lithography patterning. Ground coplanar waveguide was used for microwave structures with excellent ground planes connections due to easy via holes implementation. We present results of high frequency packaging of important RF blocks, such as integrated broadband bias-T, transimpedance amplifier ICs and silicon photonics optical modulators. The paper demonstrates a solution for high frequency hybridization that can be implemented with standard substrates, designed with any shape and with large numbers of metalized via holes and compatible with usual assembling techniques.

Al₂O₃ coatings were prepared by cathode plasma electrolytic deposition (CPED) in the solutions containing Al(NO₃)₃ · 9H₂O, polyethylene glycol (PEG) and hydrosol treated at different conditions. It was found that the deposition efficiency of Al₂O₃ coatings could be improved by adding PEG in Al(NO₃)₃ solution and hydrosol treatment of the Al(NO₃)₃ solution respectively, while the deposition efficiency was synergistically enhanced by both together. It was proved that Al₂O₃ gel was formed in the solution after hydrosol treatment. Therefore, there is a synergistic effect of PEG and Al₂O₃ gel on preparing Al₂O₃ coating by CPED. Such synergistic effect can be mainly attributed to the formation of thin gas sheath on the cathode surface under the action of PEG and Al₂O₃ gel together. Consequently, at 120 V, the over-potential in the gas sheath is decreased, while the over-potential in Al₂O₃ coating is increased. At the same time, the current density of the cathode is decreased, so a thick Al₂O₃ coating can be prepared by CPED in an effective way.

The influence of Ba doped zinc oxide films were investigated by nebulizer spray pyrolysis technique at 673 K. X-ray diffraction reveals the polycrystalline hexagonal (wurtzite) crystal structure with (0 0 2) preferential orientation. Energy dispersive spectroscopy confirms the presence of Ba, Zn and O elements in the films. Field emission scanning electron microscopy shows that the surface morphology of the nanocrystalline films were changed from spherical shape structure to flake net-like shape and sprout like spherical structure with average grain size is ~100 nm due to the critical doping concentration. PL spectra prominent peaks corresponding to near band edge UV emission and intrinsic defect of the visible blue light region and defect related deep level green emission regions were discussed. The films are highly transparent in the visible region with a transmittance higher than 74%, and have an optical band gap energy values are increased from 3.22 eV to 4.02 eV depending on the Ba doping concentration. Interparticle like grains, grain boundary effect of deposited films is studied by complex impedance spectroscopy.

Aluminum oxide (c-Al₂O₃) films are deposited for various (0.5, 1, 1.5 and 2 mbar) oxygen pressures on glass substrates by thermal evaporator. The x-ray diffraction patterns exhibit the development of single diffraction peak related to c-Al₂O₃ phase which grows along (2 2 0) orientation up to 1.5 mbar pressure. For 2 mbar pressure, the deposited film becomes amorphous because no diffraction peak is observed. A minimum FWHM and maximum crystallite size of c-Al₂O₃ (2 2 0) plane is observed for 1 mbar pressure. The enhanced crystallite size of c-Al₂O₃ (2 2 0) plane is responsible to decrease the dislocation density and residual stresses developed during the deposition process. The field emission scanning electron microscopic analysis reveals the formation of smooth, uniform and compact films showing uniform distribution of nano-particles of different shapes and sizes. The energy dispersive x-ray spectroscopic analysis confirms the presence of Al whose content is decreased with the increase of oxygen pressures. The ellipsometric analysis confirms that the refractive index and the thickness of c-Al₂O₃ film deposited for 0.5 mbar pressure are found to 1.685 and 124.43 nm respectively. In short, the crystal structure, surface morphology, film thickness and refractive index of c-Al₂O₃ films are associated with the increase of oxygen pressures.

This investigation reports on room temperature ferromagnetism in pristine and C ion implanted CeO₂ thin films deposited on Si (111) substrates by the radio frequency (RF)-sputtering method. X-ray diffraction analysis shows that the face-centered cubic (FCC) structure corresponds to CeO₂. The Raman spectra further confirm the formation of phase and also indicate the presence of defects, mainly oxygen vacancies, in these films. The presence of C is evident from Rutherford backscattering studies. Atomic force microscopy images indicate that the surface roughness values of the films reduce after C ion implantation. It is observed that the magnetic properties in CeO₂ thin films are enhanced by C ion implantation. The saturation magnetization of the pristine film increases from ∼7 emu cm⁻³ to ∼27 emu cm⁻³ for a fluence of 6 × 10¹⁶ ions cm⁻². It is also observed that the coercivity values change after C ion implantation and reduce for a film with an ion fluence of 6 × 10¹⁶ ions cm⁻² compared with other films. Mechanisms such as the F-center exchange (FCE) model are considered when attempting to understand the enhanced ferromagnetism of C ion implanted CeO₂ thin films.

Cu₂O thin films were prepared on a Cu substrate with a room-temperature water bath in which a HF and HNO₃ mixture was used as the soak solution and dilute nitric acid was used as the deposit liquid. The influences of the preparation conditions, such as the molar ratio of HNO₃:HF, the reaction temperature and the reaction time on the photoelectric performance of the sample under simulated sunlight, were explored. The results of x-ray diffraction, scanning electron microscopy, energy dispersive analysis and x-ray photoelectron spectroscopy indicate that the surface of the Cu substrate was oxidized to Cu₂O, which serves as a nanocomposite thin film. Additionally, the formation of a binary Cu₂O/Cu nanocomposite in optimized conditions exhibits its potential for excellent photoelectric properties under simulated solar illumination.

Oxidation of MoO₂/MoS₂ core–shell nanoflakes (NFs) has been investigated in different oxidation ambients i.e. oxygen (O₂) gas and its plasma. Core–shell nanoflakes are oxidized at temperatures varying from 150 °C to 450 °C and the effect of oxidation temperature on the structural and morphological changes of nanoflakes are investigated systematically. High-resolution transmission electron microscopy (TEM) images show that shell of nanoflake is oxidized with varying thicknesses and strongly depending upon the temperature and ambience. X-ray diffraction (XRD) and Raman analysis revealed the formation of MoO₃ at low temperature (⩽150 °C) in O₂ plasma. Whereas, in O₂ gas at a relatively higher temperature (⩾350 °C). Scanning electron microscopy (SEM) results show noticeable changes in the morphology as deformation of nanoflakes after oxidation. X-ray photoelectron spectroscopy (XPS) revealed, oxidizing in O₂-plasma led to multiple oxidation states of Mo (4⁺, 5⁺, and 6⁺) and S (2⁻, 6⁺). It is evident that the extent of oxidation of MoS₂ shell is higher in plasma due to reactive species of oxygen (O⁺, $\text{O}_{2}^{+}$, O^*, etc), as compared to O₂ gas.

Recently, hard AlMgB₁₄ (BAM) coatings were deposited for the first time by RF magnetron sputtering using a single stoichiometric ceramic target. High target sputtering power and sufficiently short target-to-substrate distance were found to be critical processing conditions. They enabled fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 GPa and 275 GPa at 200 nm depth in 2 µm thick film (Grishin et al 2014 JETP Lett. 100680). The narrow range of sufficiently short target-to-substrate distance makes impossible to coat non flat specimens. To achieve ultimate BAM films' characteristics onto curved surfaces we developed two-step sputtering process. The first thin layer is deposited as a template at low RF power that facilitates a layered Frank van der Merwe mode growth of smooth film occurs. The next layer is grown at high RF target sputtering power. The affinity of subsequent flow of sputtered atoms to already evenly condensed template fosters the development of smooth film surface. As an example, we made BAM coating onto hemispherical 5 mm in diameter ball made from a hard tool steel and used as a head of a special gauge. Very smooth (6.6 nm RMS surface roughness) and hard AlMgB₁₄ films fabricated onto commercial ball-shaped items enhance hardness of tool steel specimens by a factor of four.

Nanostructured ZnO–Co and ZnO films with Pt, Cu, and Co as top electrodes, and Pt as bottom electrodes were grown by magnetron sputtering. Both ZnO–Co and ZnO films show bipolar resistive switching characteristics. The resistive switching properties of ZnO films are strongly dependent on the top electrode materials. The effect of top electrodes on resistive switching of ZnO–Co films is weakened due to the dominant roles of Co particles in the films. It is different with ZnO films that the ZnO–Co film shows a forming-free process. The calculation from the classical electromagnetism theory indicates that the existence of Co nanoparticles in the ZnO switching matrix can enhance the local electrical field to some extent, and decrease the operating voltages. So the device with a ZnO–Co film as a switching matrix can significantly reduce power consumption, weaken the dependence of the electrode materials, and optimize the resistive switching performance.

In this work, a high density (94%) and high electron concentration (2.3  ×  10²⁰ cm⁻³) doped C12A7 electride ceramic target for magnetron sputtering was prepared by directly heating the C12A7 nano powder to above its melting point. The effects of the temperature on the electron concentration was explored. Furthermore, a smooth (R_q  =  0.6 nm), high transparent and low work function (Φ  =  2.9 eV) C12A7 electride thin film was deposited via magnetron sputtering. This result provides a suitable route for the fabrication of large-scale C12A7 electride film and has a bright prospect for application in optoelectronic devices.

Photocatalytic properties of anatase and other TiO₂ polymorphs are widely researched and applied in practical application. In current study TiO₂ films on the plasma pre-treated expanded polystyrene (EPS) foam were deposited using magnetron sputtering technique. Main properties of the films were characterised using combination of XRD, XPS and SEM techniques. Photocatalytic properties of the observed crystalline anatase phase were tested by investigating bleaching of the methylene blue (MB) aqueous solution and by testing Escherichia coli (E. coli) viability after incubation under UV-B irradiation. E. coli viability experiments indicated that there are two mechanisms of E. coli bacteria inactivation. UV irradiation alone causes rapid damage to the outer membrane of E. coli bacteria. The second mechanism of E. coli inactivation is invoked only with synergistic combination of TiO₂ and UV. Acting as photocatalyst TiO₂ generates active radicals who initiate the chain peroxidation of organic molecules and within 45 min reduce E. coli bacteria viability by nearly 90%.

Three-step pulse electrochemical deposition was used to deposit FeS_xO_y thin films on indium–tin-oxide-coated glass substrates at room temperature from solution containing Na₂S₂O₃ and FeSO₄. The deposition was conducted under two different potential shifts direction (condition A: from negative to positive and condition B: from positive to negative) with intermediate potential V₂ variation. All the deposited films were amorphous. In Raman measurements, peaks attributed to marcasite and Fe_1+xS were observed. The O/Fe ratio is larger than unity. The films deposited under condition A with an intermediate potential V₂  =  −0.6 V and condition B with V₂  =  −0.4 V showed a band gap which is estimated around 2.3–2.45 eV, larger than literature value of Fe₂O₃ (2.1 eV). In the photoelectrochemical measurement, nearly intrinsic behavior was confirmed.

The LF6 aluminum alloy plates were joined by friction stir welding method. The tool rotational (1180 rpm) and transverse speed (0.56 mm s⁻¹) were kept constant during welding of 4 mm thick plates. The microstructural features, hardness and tensile properties of the welded samples were determined to evaluate the structural integrity in comparison with the base metal. The electrochemical behavior of base metal (BM), thermo-mechanically affected zone (TMAZ) and weld nugget zone (WNZ) was also investigated by potentiodynamic polarization and electrochemical impedance spectroscopy in 3.5% NaCl solution. The microstructural study revealed significant grain refinement and agglomeration of β (Mg₂Al₃) intermetallic precipitates in the WNZ. The relatively higher hardness and a decrease in the ductility (3%) also assured the formation of precipitates β precipitates in the WNZ welded samples. The fracture surface of welded sample also revealed the existence of β precipitates within the elongated dimples which may be considered as the crack initiation sites. The relatively lower corrosion rate (23.68 mpy) and higher charge transfer resistance (403 Ω cm²) of BM compared to WNZ could be associated with the galvanic dissolution of Al-matrix through competitive charge transfer and relaxation (adsorption/desorption of intermediate species) processes specifically at the vicinity of the β precipitates.

This study proposed a new method for coating tungsten–copper alloy to copper surface. First, the tungsten–copper alloy powder was pre-compacted to the copper surface. Then, the powder in the hydrogen atmosphere was sintered, and the pre-compacted powder was compacted by explosive compact-coating. Finally, diffusion sintering was conducted to improve the density of the coating layer. The theoretical density of the coating reached 99.3%. Microstructure characteristics indicated that tungsten and copper powders were well mixed. Tungsten particles were larger than copper particles. Scanning electron microscope (SEM) fracture surface analysis was different from the traditional fracture of metals. Coating and substrate joint surfaces, which were analyzed by SEM, indicated that the tungsten–copper alloy was sintered on the copper surface. The hardness of the coating layer was 197.6–245.2 HV, and the hardness of the substrate was approximately 55 HV.