Table of contents

The behavior of a liquid on a solid surface has shown great interest in a variety of applications related to surfaces and its interfaces. In this paper, the wetting behavior of DI water on micropatterned silicon surfaces fabricated through photolithography and deep reactive ion etching (DRIE) is investigated. Micro pillars of both solid and hollow geometries at a varying pitch and its arrangement in an array has been examined with static contact angle measurement. However, the results concluded that the arrangement of pillars in an array plays an important role as hollow geometries in the case of chain type arrangement provide both hydrophilic and hydrophobic surface properties, while the same hollow geometries in case of zig-zag orientation experiences only hydrophobicity at a varying pitch. Decreased WCA with increased pitch has been observed in the case of a zig-zag arrangement, due to the effect of capillary and gravitation forces. Also the existence of air pockets at sharp corner in the case of hollow square assists in providing maximum contact angle (WCA = 144°) as compared to hollow circle and solid geometries; thus a non-sticky behavior would be possible between the droplet and the patterned surface, due to less adhesion force.

Magnesium and its alloys are suitable candidates for developing biodegradable metallic implants. However, the rapid degradation of these alloys in the physiological environment is a major limitation for such applications. In this work, Mg–Ca alloy was chemically treated with acetic acid and its effects on degradation behaviour were studied using simulated body fluid (SBF). The surface morphology and composition of the acid pickled samples were investigated using a scanning electron microscope (SEM) and infrared spectroscopy (IR). The degradation rate was analysed by conducting potentiodynamic polarization (PDP) and immersion tests. The results show that optimum acetic acid treatment improved the corrosion resistance by acid etching and formation of magnesium acetate layer. The treated samples also exhibited enhanced biomineralization and developed calcium phosphate layer on the surfaces during immersion tests. It is proposed that acetic acid pickling can be used as a reliable technique for surface modification as well as for pre-treatment of magnesium alloys to make them suitable for degradable metallic implant applications.

Metal-organic framework (MOF) of Ni-MOF, Co-MOF, and Ni/Co-MOF were synthesized by a facile hydrothermal method using Trimesic acid as structure directing linker. The physico-chemical properties of the synthesized MOFs were characterized by P-XRD (powder X-ray diffraction), FT-IR (fourier transform infrared spectroscopy), SEM-EDS (scanning electron microscopy/energy-dispersive X-ray spectroscopy), HR-TEM (high-resolution transmission tlectron microscope) and BET (Brunner Emmett Teller) surface area techniques. The supercapacitance performance of these MOFs were studied by electroanalytical techniques such as cyclic voltammetry (CV), chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). Amongst the MOFs investigated, Ni/Co-MOF exhibited highest specific capacitance (C_s) of 2041 F g⁻¹ at a scan rate of 2 mV s⁻¹ and 980 F g⁻¹ at a current density of 2.5 A g⁻¹. Ni/Co-MOFs delivered a maximum energy density (ED) of 55.7 W h Kg⁻¹ at a corresponding power density (PD) of 1 K W kg⁻¹ and maximum PD of 9.8 K W kg⁻¹ at an ED of 41.6 W h Kg⁻¹. An outstanding supercapacitance performance with superior columbic efficiency of 98.4% and capacitive retention of 73% after 5000 cycles marks this material as potential candidate for supercapacitors (SCs). A comparative electrochemical study of these MOFs were made in three electrode system, further electrochemical performance was corelated with their physico-chemical properties.

In this paper, a Self-consistent Orthogonalized linear combination of atomic orbitals (OLCAO) technique with a generalized gradient approximation such as Perdew–Burke–Ernzerhof Solid (GGA-PBE SOL) has been used to scrutinize the structural, optical, electronic and mechanical properties of normal pressure phase (Anatase and Rutile) and high pressure phase i.e., cubic (Fluorite and Pyrite) TiO₂. Electronic and optical properties of normal pressure phases of TiO₂ are also investigated using (Meta) MGGA-Tran and Blaha (TB09) and obtained results are a close approximation of experimental data. It is seen that the virtually synthesized structural parameter for cubic and tetragonal phases of TiO₂ are consistent with experimental and theoretical data. From the effective mass of charge carriers (m*), it can be observed that pyrite TiO₂ is having lower effective mass than the fluorite and hence shows higher photocatalytic activity than fluorite. Furthermore, it is seen that fluorite is more dense than anatase, rutile and pyrite TiO₂. From the theoretical calculations on the optical properties, it can be concluded that optical absorption occursin the near UV region for high and normal pressue phases of TiO₂. Again from the reflectivity characteristics R(ω), it can be concluded that TiO₂ can be used as a coating material. Elastic constants, elastic compliance constants, mechanical properties are obtained for anatase, rutile, fluorite and pyrite TiO₂. A comparison of the results with previously reported theoretical and experimental data shows that the calculated properties are in better agreement with the previously reported experimental and theoretical results.

In order to realize low-cost and efficient organic light-emitting diodes (OLEDs), the transparent anode should have excellent optical and electrical properties, among other factors. Typically, transparent conductive oxides have been widely used for transparent top electrodes, but they suffer from several drawbacks. We herein report the fabrication of efficient indium-free transparent OLEDs using metal-mesh based top electrodes, made of any metal of choice, Au, Ag or Cu. The fabricated devices on inch square substrates exhibited superior emission characteristics without any color shift. In terms of workfunction matching, Cu did the best. With a Cu-TCE of low sheet resistance (∼7 Ω sq⁻¹), uniform emission characteristics were achieved with relatively high current efficiency and luminance, comparable to those from the ITO based devices.

Strategies are suggested for the waste utilization of industrial leather by preparing composites with epoxy and high-density polyethylene (HDPE). The addition of leather improves the average specific compression toughness of epoxy by 29%. The fracture surface analysis suggests the incorporation of leather microparticles leads to a transition of failure mode of epoxy from brittle to ductile. In addition, the dynamic strength of the leather/epoxy composite is found to be 69% higher than that of neat epoxy. However, no significant changes are observed when HDPE is infiltrated with leather. Apart from dispersing the leather particles directly in polymer, a novel strategy is presented here in which leather/HDPE microfibers are prepared and then used to reinforce the epoxy matrix. The specific compression modulus of this composite blend is 8% and 65% higher than epoxy and HDPE, respectively. Fractography is further carried out on the failed specimens to understand the failure mechanism in each composite. A change in the failure mode is observed when epoxy is reinforced either with leather particles or the microfiber. While the failure strength of the microfiber is found to be higher than epoxy, the strength of microfiber/epoxy interface is lower than that of epoxy.

This study reports the properties of green mediated synthesized iron oxides nanoparticles (Fe₃O₄ NPs) from peel extracts of pomegranate plant and its polyacrylonitrile/iron oxide composite nanofibers (Fe₃O₄/PAN). The following were used to characterize the synthesized nanoparticles and its polymer nanofibers; FT-IR, UV-Visible spectroscopy, scanning electron microscope SEM, TEM and cyclic voltammetry. The antimicrobial activities of synthesized nanoparticles were investigated against selected bacterial pathogens. For the plant extract, FTIR revealed OH characteristics peaks at 3271 cm⁻¹ and 1600 cm⁻¹ while the absorption peaks at 577 and 430 cm¹ showed successful reduction of the precursor to Fe₃O₄ nanoparticles. The SEM images showed a spherical morphology of Fe₃O₄ and that of the composite with entrapped Fe₃O₄ into the PAN nanofibers. Photocatalytic process showed that the synthesized Fe₃O₄ nanoparticles has degradation efficiency of 71.36% and the nanofibers exhibited efficiency of 22.68% towards methylene blue (MB) dye. However, further kinetic analysis of the degradation process put Fe₃O₄/PAN nanofibers (NF) at a better correlation coefficient of 0.9239 than the Fe₃O₄ nanoparticles. Electrochemical studies using cyclic voltammetry showed that PAN functionalized with Fe₃O₄ is more electroactive as compared to the other electrodes studied. The anodic peak potential at 599 mV also confirmed the presence of Fe₃O₄ in the nanocomposite Fe₃O₄/PAN. The antimicrobial studies revealed that as the concentration of the green mediated Fe₃O₄ nanoparticle increases in the composite Fe₃O₄/PAN an excellent antimicrobial activity against selected pathogens were observed, showing Fe₃O₄ nanoparticles potentials to control pathogens of public health significance.

Nanoparticles usage are now emerging as hazardous nanopollutants due to inappropriate usage and improper disposal. Superparamagnetic Iron Oxide Nanoparticles (SPIONs) is a widely used nanoparticle with various applications. In this study, SPIONs was evaluated for its impact against Vigna radiata and Eudrilus eugeniae. SPIONs were synthesized by chemical co-precipitation method in presence of cobalt chloride. The produced SPIONs was characterized using UV-Visible Spectroscopy, SEM (Scanning electron microscopy), EDX (Energy dispersive X-ray spectroscopy), XRD (X-ray diffraction), TEM (Transmission electron microscopy), AFM (Atomic force microscopy), XPS (X-ray photoelectron spectroscopy) and Zeta potential. The synthesized SPIONs were crystalline and monodispersed with size ranging between 15 nm and 20 nm. The seedlings of SPIONs treated Vigna radiata were found to have reduced root and shoot growth. The bioaccumulation of iron oxide in the treated plants was confirmed by ICP-OES (Inductively coupled plasma - optical emission spectrometry) analysis and Prussian blue staining. Cellular destruction and reduced reproduction rate were found in SPIONs exposed Eudrilus eugeniae and ICP-OES analysis of earthworm samples affirmed the bioaccumulation of SPIONs.

Cellulose nanocrystals (CNCs) are excellent candidates for the design and development of multifunctional biomaterials systems to be used in a variety of technologically relevant applications. They may be used as the structural reinforcement phase of polymer matrices, act as catalyst support constituents, as well as drug delivery vectors. Modifying and functionalizing CNCs by introducing specific functional components can impart electronic, magnetic, catalytic, fluorescence and optical properties to the system. In this work we report the successful in situ tethering of iron oxide nanoparticles (IONPs) onto CNCs by the thermal decomposition of Fe(CO)₅ in a H₂O/DMF suspension. Following this procedure, IONPs consisting of mixtures of Fe₃O₄ and Fe₂O₃ with an average diameter of 20 nm were attached to the CNCs. The type of iron oxide species that was generated was determined by selected area electron diffraction (SAED) and energy dispersive spectroscopy (EDS), and the particle size was evaluated by transmission electron microscopy (TEM). Raman spectroscopy was used to characterize the presence and the nature of the molecular interaction between the IONPs and the CNCs.

Emerging antibiotics resistance fungal infectionsis a major global health problem and new antifungal formulations are direly needed to fight drug resistant Candida albicans strains. This study is aimed to synthesize effective antifungal nanostructures of cerium oxide (CeO₂) using culture filtrates of two common fungal strains Aspergillus terreus and Talaromyces pupureogenus. The fungal strains used in the synthesis were identified by 18S rRNA gene sequencing and deposited to NCBI GenBank with the accession number of MN099077 and MN121629, respectively. The biofabricated CeO₂ NPs were characterized by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM). Pure CeO₂ nanoparticles (NPs) synthesized using Aspergillus terreus culture filtrate were depicted spherical morphology with average size of 28.5 nm. The CeO₂NPs synthesized using Talaromyces pupureogenus revealed the presence of nanosponges with average size of 21.4 nm. Gas chromatography mass spectrometry of culture filtrates of respective strains indicated the presence of ethanol, 1-propanol and tri-chloromethane in culture filtrate of Aspergillus terreus and with addition of palmitic acid in Talaromyces pupureogenus culture filtrate which may have a function as bio reducers and capping agents. Dose dependent anticandidal activity of CeO₂ NPs using various different concentrations (100, 200, 300, 600 μg ml⁻¹) synthesized by both fungal strains was observed by disc diffusion assay against Candida albicansas evidenced by increase in size of zone of inhibitions with increasing concentration of CeO₂NPs. Further in-vitro and in-vivo experiments are required to access the potential of CeO₂ NPs for controlling Candida albicans strains.

The adsorptions of toxic gases including NO₂, HCN, HCHO and CO molecules on the pristine and amine functionalized (5,0) single-wall boron nitride nanotubes (BNNTs) are investigated based on self-consistent charge density functional tight-binding (SCC-DFTB) method. The calculated results indicate that the pristine (5,0) BNNT exhibits weak adsorption for the gas molecules. Based on the calculated adsorption energy, interaction distances and charge transfer, amine functionalization at a boron atom of the pristine (5,0) BNNT enhances the sensitivity of the pristine (5,0) BNNT toward the gas molecules. The electronic densities of state results reveal that new local states in the vicinity of Fermi level for adsorption between amine functionalized BNNT and the gas molecules significantly appear. This confirms the improved sensitivity of the pristine (5,0) BNNT functionalized with amine for adsorption of the toxic gases. This study is expected to provide a useful guidance on gas sensing application of pristine and amine functionalized BNNTs for detection of the toxic gases at room temperature.

Zeolites are aluminosilicates with extensive application both commercially and in materials science. Current applications include dehydrating natural gas and in humidity sensors. Synthesis of new frameworks is an important area of research in chemistry and materials science. The Zeolite LTA framework in particular is getting much attention in this area due to its potential for application. Topological indices are graph invariants which provide information on the structure of graphs and have proven very useful in quantitative structure activity relationships (QSAR) and quantitative structure property relationships (QSPR) at predicting important chemico-phyiscal aspects of chemical compounds. In this paper we compute nine of the most significant distance based topological indices of the Zeolite LTA framework and thirteen valency based molecular descriptors.

In this study, gum polysaccharide of Azadirachta indica was extracted and purified. The obtained polysaccharide was subjected to TLC chromatography, spectroscopic analysis, thermogravimetric analysis and GC-MS analysis. The polysaccharide was found to have Glucose, Idosan, Allose, Galactose, Ribose and Xylose. The polysaccharide was not having antibacterial activity but possessed good antioxidant and anticancer activity. The extracted polysaccharide was further carboxymethylated and used for the synthesis of nanocarrier to carry anticancer drug, curcumin. Size of the drug unloaded nanocarrier were found to be size below 40 nm, whereas the drug loaded nanocarriers were around 50 to 70 nm. The nanocarriers were studied for cytotoxicity against MCF7 cancer cell line and found to be effective.

Herein, the Attapulgite nanoparticles (ATP NPs) coated silk fabric was prepared by impregnation method using hyperbranched polymer as addition agent. The ATP NPs and prepared silk fabrics were characterized by means of scanning electron microscope (SEM), ultraviolet-visible (UV–Vis) spectroscopy, Fourier transform infrared spectrophotometer (FTIR), X-ray diffraction (XRD), Energy Dispersive Spectrometer (EDS). The results of SEM, EDS, FTIR and XRD confirmed that ATP NPs were successfully coated on the surface of silk fabric. Not only did the treated silk fabrics possess excellent antibacterial property and antibacterial resistance, but also exhibited outstanding anti-ultraviolet performance, which can meet the requirements of multifunctional products.

This paper reported a simple approach to prepare robust conductive/superhydrophobic coating. The hierarchical structure was obtained through the addition of microscale filler (graphite powder and expanded graphite) and nanoscale filler (carbon nanotube). The self-similar structure was obtained through bonding the fillers using the epoxy matrix. Through the combination of the hierarchical and self-similar structures, the as-prepared superhydrophobic coating demonstrated excellent anti-abrasion property, good conductivity, excellent self-cleaning performance in both oil and water environment, outstanding anticorrosive property, and superior thermal stability simultaneously. Moreover, this superhydrophobic coating was achieved by a simple casting method, which has the potential to be used in large scale production.

This research reports the optimization of the synthesis of bacterial nano cellulose (BNC) from banana peel waste media of Kepok bananas (Musa paradisiaca L.) using Gluconacetobacter xylinus bacteria in a fermentation process for use in water filter membrane applications. Bacterial nanocellulose (BNC) synthesis was successfully accomplished under conditions of pH 4, 0.5% urea, and varying sucrose contents (5%, 10% and 15% (w/v)). The higher sucrose content causes the pH of the banana peel extract solution to decrease at the end of Day 8 and 10 due to the metabolic activity of bacteria, which produces acetic acid. A bacterial growth pH range of 3.93–4.26 was obtained. The Optical Density (OD) values tend to increase with respect to fermentation time due to the growth of BNC-forming bacteria. The higher the added sucrose content, the higher the total amount of the acid obtained as the G. Xylinus bacteria produces acetic acid in its metabolic processes. BNC thickness is directly proportional to the increase in sucrose level but does not increase proportionally with the increase in sucrose levels from 5%, 10% (two times), and 15% (three times). The sucrose level at 5% (w/v) produces most optimal results. Optimal incubation time was obtained on Day 6, which had the highest rate of increase in thickness in addition to the supporting pH, OD value and total acid factors. The TEM analysis shows that the BNC surface morphology tends to be the same among all sucrose level (5%, 10% and 15% (w/v)). The difference can only be seen in the density of the nanocellulose. The nanocellulor nanofiber produced from banana peels has diameter sizes between 30–50 nm which potentially be used in water filter membrane application.

α-Fe₂O₃/MoS₂/rGO nanocomposites was prepared by a two-step hydrothermal method and characterized by XRD, FESEM, EDS, FTIR, and UV–vis absorption spectroscopy. The results confirmed the formation of α-Fe₂O₃/MoS₂-rGO (10 wt%) nanocomposites were composed of hematite nanoparticles with particle size of 30 nm and MoS₂/rGO composite nanosheets with maximum sheet thickness of ∼ 10 nm. Upon addition of MoS₂-rGO (8.0 wt%) nanosheets, the band gap of α-Fe₂O₃ nanoparticles decreased from 2.3 to 1.7 eV that was accompanied by light absorption enhancement. Owing to synergetic effect between rGO and MoS₂ nanosheets leading to suppression of charge carrier recombination, prolongation of charge carrier lifetime, improvement of the interfacial charge transfer and increase in the number of active sites in α-Fe₂O₃ nanoparticles, as-synthesized α-Fe₂O₃/MoS₂-rGO (10 wt%) nanocomposites nanocomposite showed highly enhanced photocatalytic performance for Rh B degradation under light irradiation so that complete degradation of Rh B organic dye was achieved within 30 min.

The characteristics of Silicon carbide (SiC) and multi-walled carbon nanotube (MWCNT) nano composite coatings by a Pulse Reverse Electrodeposition (PRE) method is investigated in detail to enhance the microhardness (MH) and corrosion resistance characteristics of AISI 304 stainless steel substrate. The electrodeposition nature, dissolution behavior, surface characteristics are assessed by Scanning Electron Microscopy (SEM) with energy dispersive x-ray (EDX), x-Ray Diffraction (XRD), Atomic Force Microscopy (AFM), Microhardness (MH) Test and Electrochemical studies. The coatings are prepared in the watts type bath using pulse reverse electrodepositions (PRE) method of varying the electrolyte deposition parameters in different combinations. Present results clearly reveal that, there is a drastic improvement in the magnitude of microhardness of coated specimens, silicon carbide (SiC) and multi-walled carbon nanotube (MWCNT) composite coatings yield a maximum hike of 91.6% and 168% respectively. Furthermore, the Nyquist and impedance plots clearly depict that, multi-walled carbon nanotube (MWCNT) exhibits higher corrosion resistance characteristics.

This paper presents the fabrication of self-organized ZrO₂, TiO₂, and α-Fe₂O₃ nanotube arrays by anodization of Zr, Ti, and Fe foils, respectively in fluoride-containing EG electrolyte at 40 V for 20 min. The as-anodized nanotubes were annealed in a tube furnace at 400 °C for 3 h to induce the crystallization of the oxide film. Morphology, crystal structure, surface properties, and optical properties of the anodic ZrO₂ nanotubes (ZNTs), TiO₂ nanotubes (TNTs), and α-Fe₂O₃ nanotubes (FNTs) were characterized by Field-Emission Scanning Electron Microscopy (FESEM), Transmission Electron Microscopy (TEM), x-ray Diffraction (XRD), Fourier-Transform Infrared (FTIR) spectroscopy, Photoluminescence (PL) spectroscopy, and UV–visible Near-Infrared Diffuse Reflectance Spectra (UV–vis NIR DRS) spectroscopy, respectively. Based on the FESEM and TEM micrographs, ZNTs possessed the longest nanotubes (i.e. 9.6 μm) compared with TNTs and FNTs under the same anodization condition. The aspect ratio of the nanotubes can be arranged in the order of ZNTs > FNTs > TNTs. The surface of the annealed ZNTs, FNTs, and TNTs was enriched with –OH groups to facilitate the Cr(VI) adsorption. According to the UV–vis NIR DRS spectra, strong visible light absorption was observed on the FNTs due to their low band gap. Whereas, the TNTs predominantly absorbs the UV light at λ_max = 360 nm. Rapid Cr(VI) removal was observed on FNTs, i.e. 100% after 2 h activated by sunlight with negligible Cr(VI) removal for ZNTs and TNTs. When exposed to UVC (λ = 254 nm), only 39% versus 37% Cr(VI) removal efficiencies were obtained on TNTs and ZNTs after 3 h suggesting sluggish electron transfer due to rapid charge carriers recombination as evident in the PL spectra.

A series of Mn–Co–Ni–O/LaMnO₃ composite materials were synthesized through the sol-gel method. The structure of these powders changed from the spinel to a spinel–perovskite mixed phase as the content of LaMnO₃ increased from 0 to 50%. Meanwhile, some grains of composite material were refined to form many small particles and distributed among the porous microparticles. According to the absorption spectra of composite samples, the strong absorption structures appeared in visible ranges, especially between 400 and 730 nm. The photocatalytic degradation of tetracycline under the visible light irradiation indicated that the percentage of LaMnO₃ at 50% exhibited the highest degradation rate (70.2%) in 150 min. Its high photocatalytic activity was mainly due to the large surface area, strong visible light absorption and increased ratio of Mn³⁺/Mn⁴⁺ ions. These new micro-structured photocatalysts were expected to show considerable potential applications in the water treatment.

In this work we use the Two Temperature Model coupled to Molecular Dynamics (TTM-MD) to study swift heavy ion irradiation of W finite nanowires. Au projectiles are considered with energies ranging from 20 to 50 MeV, which correspond to electronic stopping values less than 20 keV nm⁻¹ in the regime where electronic stopping is larger than nuclear stopping. Nanowires with diameters much smaller than the electron mean free path are considered for two different sizes with an aspect ratio ∼3.7 between length and diameter. Nanowires display radiation-induced surface roughening, sputtering yields and the formation of point defects and di-vacancies. For the smallest size, a hole stays opened in the central part of the wire for S_e > 12.6 keV nm⁻¹. W nanofoams, considered as collections of connected nanowires like those simulated here, are expected to behave similarly under irradiation displaying radiation resistance for the electronic stopping range that has been considered. In fact, nanowires larger than tens of nm would be needed for defect accumulation and lack of radiation resistance.

The biogenic/green silver nanoparticles (g-Ag NPs) were synthesised by using the extract of indigenous medicinal plant of Ethiopia, Hagenia abyssinica (Brace) JF. Gmel. leaf extract for the first time, to investigate the synergistic effect of biomolecules towards the enhancement of electrochemical properties of NPs. The synthesized g-Ag NPs were characterized by UV-visible, UV-DRS, FT-IR, XRD, SEM, EDXA, TEM, HRTEM and SAED techniques. The maximum absorbance, λ_max was found to be 461 nm for g-Ag NPs due to surface plasmon resonance. The energy gap, E_g of NPs, was found to be 2.31 eV. FTIR spectrum confirmed the presence of bioactive compounds responsible for possible capping and stabilisation of g-Ag NPs. The XRD analysis revealed that the g-Ag NPs are highly crystalline exhibiting sharp peaks for (111), (200), (220) and (311) planes in the diffraction pattern. SEM and TEM micrographs showed differently shaped Ag particles in addition to spherical shape. The average particle size of NPs was found to be 24.08 nm using imageJ analysis. EDX analysis confirmed the presence of Ag in the g-Ag NPs. In addition, the SAED pattern of g-Ag NPs presented concentric patterns for 4 major planes of crystalline silver. The d-spacing values of 0.2428 nm, 0.2126 nm, 0.1483 nm and 0.1263 nm corresponds to d₁₁₁Ag, d₂₀₀Ag, d₂₂₀Ag and d₃₁₁Ag lattice fringes respectively. The cyclic voltammetry (CV) results suggest that g-Ag NPs possess better electrochemical properties due to its lower charge transfer resistance value of 17 Ω. EIS studies too revealed better stability of g-Ag NPs as electrode materials.

The present research informs about the synthesis of gold nanoparticles (AuNPs) through Ultrasonic Spray Pyrolysis (USP), which were collected in ethanol with 0.1% Polyvinylpyrrolidone (PVP). Initially, the research focused on two precursors, where the first represented a homemade H-HAuCl₄, completed in our own laboratory through the chlorine gas method by using HCl and KMnO₄, and the second was the commercial C-HAuCl₄, prepared by using Gold (III) chloride tetrahydrate powder and deionised water. The goal was to find any potential precursor differences and their influences on the later use for AuNPs synthesis through USP using almost the same parameters. In the first step of research it was determined that the H-HAuCl₄ precursor was similar to C-HAuCl₄ in chemical composition, surface tension and pH value. This finding represented the starting point for being able to use H-HAuCl₄ in the USP for AuNPs' synthesis. In the second step, AuNPs were synthesised from both types of precursors. Afterwards, characterisation of some functional properties by FTIR and UV–vis techniques was done directly for H- and C-AuNPs in the collecting media. For SEM/EDX and TEM microscopy both types of H- and C-AuNPs were dried, and observation revealed that the morphology, shape and size distribution of dried AuNPs were very similar. Based on the performed laboratory research, it could be concluded that prepared H-AuNPs could represent a new and low-cost effective solution for future USP transfer onto the industrial level, not only in in the process itself, but also in the field of Low-cost Precursor Preparation.

In this paper, we replace the sulfur atom with other atoms based on rhenium disulfide. The monolayer is combined and adjusted on the original basis. Based on the first principle, we studied the structural, electronic and optical properties of the transition metal monolayers of ReX₂ and ReXS (X = S, Se, Te). The structure resembles a 'sandwich'. It is worth noting that ReSeS and ReSe₂ not only retain the direct band gap properties, but also have a large band gap, when the strain changes, not only the band gap changes, but also the nature of the band gap changes with each other. so they show good optical properties, and ReSe₂ and ReSeS have stronger absorption in the ultraviolet band. The band gap opened in ReSeS can be effectively adjusted by biaxial strain, and the band gap varies between direct and indirect.

In this study, we produced ZnO nanoflakes (ZnO-Nfs) by using microwave-assisted techniques. The structural properties of ZnO-Nfs were analyzed by x-ray diffraction (XRD) technique, Raman scattering spectroscopy and field-emission scanning microscopy (FESEM). The Crystallite size (D) and lattice constants of ZnO-Nfs were calculated. The optical properties of ZnO-Nfs were investigated by using UV-visible diffuse reflectance spectrum and photoluminescence (PL) spectra. Also, dielectric constants of ZnO-Nfs were calculated as related to the refractive index (n) an extinction coefficient (k).

We investigate the structural, electronic and magnetic properties of LaMnO₃/BaTiO₃ heterostructure by means of ab initio calculations within the GGA+U approach. We consider the heterostructure when ferroelectric polarization in the BaTiO₃ film is oriented perpendicular to the LaMnO₃ substrate. We present atom and spin-resolved density of states calculations for LaMnO₃/BaTiO₃ heterostructure with different number of BaTiO₃ overlayers as well as layer-resolved spectra for the conducting heterostructure. We found that the LaMnO₃/BaTiO₃ heterostructure becomes conducting with a significant spin polarization indicating that the interface becomes ferromagnetically ordered. The propose concept of a ferroelectrically controlled interface ferromagnetism that offers the possibility to design novel electronic devices.

Up-conversion phosphors have attracted considerable attention for their visible-light emission. In this study, a ZnO–TiO₂ up-conversion phosphor containing Yb³⁺ and Er³⁺ ions was prepared; its emission characteristics and crystal structure were analyzed, and its nanoscale elemental mapping was examined. The metal organic decomposition (MOD) method was used to fabricate the samples. After firing the sample at 1000 °C, the emission intensity showed a maximum when the molar ratio was Ti/Zn/Yb/Er = 1/1/0.06/0.02. Finally, the function of each element was considered from the viewpoint of the crystal structure and nanoscale mapping.

In the present work, growth of single crystals of chalcone derivatives {4-[(1E)-3-(4-methylphenyl)-3-oxoprop-1-en-1-yl]phenyl 4-methylbenzene-1-sulfonate} (4M1PMS) and {4-[(1E)-3-(4-bromophenyl)-3-oxoprop-1-en-1-yl]phenyl4-methylbenzene-1-sulfonate} (4BPMS), at room temperature is reported. The spectroscopic techniques are used to identify the presence of functional groups in the materials. The single-crystal XRD and powder XRD analysis reveals that 4M1PMS belongs to non-centrosymmetric ($P{2}_{1}{2}_{1}{2}_{1}$) and 4BPMS belongs to centrosymmetric $(P{2}_{1}/n)$ crystalline system. The molecular structures exhibit C–H...O and π...π intermolecular interactions. From UV/VIS/NIR spectroscopic studies, it is found that both samples have bathochromic shifts in linear absorbance (cut-off region) spectra. The broad emission region involved in several sharp emission peaks in blue region, exhibits a blue light emission property, as observed from photoluminescence study, in both the samples. The thermal stability of the materials were studied by TGA/DTA techniques and crystals were thermally stable until the melting point. In NLO study, 4M1PMS crystal has shown SHG efficiency 2.2 times that of KDP crystal. In addition, electronic contribution in hyperpolarizability (first order and second order) tensors of both the compounds were computed theoretically by M06-2X functional at DFT level. The open/closed aperture Z-scan technique were performed to evaluate third order nonlinear optical materials by measuring experimental parameters such as nonlinear absorption/refraction and calculate second-order hyperpolarizability with corresponding third-order nonlinear optical susceptibility $({{\boldsymbol{\chi }}}^{\left(3\right)})$ of 4M1PMS and 4BPMS. The surface damage threshold studies of 4M1PMS and 4BPMS were performed by Q-switched Nd:YAG laser at 532 nm.

The replacement for synthetic fiber and other materials with natural fiber in the brake pad has become a key research area in many industries. Many production industries are always focused on natural fiber over synthetic fibers because of its advantage of biodegradability, less expensive, availability, and environment friendly. However, natural fibers cannot be used directly in composites because of its poor adhesion behavior between matrix and fiber and observe high water content in the fiber. Further, the excess water content in the inside fiber has been removed by using alkaline, benzoylation, and acetylation treatment. It has been achieved by the same chemical concentration but with different time duration. The Fourier-transform infrared spectroscopy (FT-IR) analysis revealed that the amount of cellulose content after chemical treatment was improved and decrease in other substances like hemicellulose, lignin, and wax content. X-Ray Diffraction (XRD) analysis study confirmed that the rise in the crystalline index (70.41 from 52.7) of alkali-treated SEFs at 30 min. The thermogravimetric analysis study has confirmed that the increase in the degradation temperature of Benzoyl-treated SEFs (387 °C) at 60 min when compared with untreated fiber (320 °C). The Scanning Electron Microscope (SEM) results have confirmed that the elimination of impurities from the fiber surface after chemical treatment. Further, the acetyl- treated fibers have shown that better hydrophobic properties than other treated fibers. In the above tests have been concluded that the chemically treated fibers, as one of the suitable materials for the development of the brake pad application.

A low-cost and minimal-processing-step method is demonstrated to synthesize Yb₂O₃-ZrO₂ system by laser excitation catalyzed solid-state reaction. With 980 nm CW laser irradiating, near-resonant excitation of Yb³⁺ ions can obviously enhance solid state reaction. As the molar content of Yb₂O₃ rises from 12.5% to 50%, the lattice parameter of Yb₂O₃-ZrO₂ ceramic increases distinctly. Among them, high crystal quality of Yb₂Zr₂O₇ and Yb_0.2Zr_0.8O_1.9 are synthesized at the laser power of 400 W for 10 s. Two obvious Raman peaks of Yb₂Zr₂O₇ represent increased Raman activity. X-ray photoelectron spectroscopy (XPS) and Impedance spectroscopy demonstrate the huge amount of the oxygen vacancies in Yb_0.2Zr_0.8O_1.9. Yb₂Zr₂O₇ shows lowest thermal conductivity among all the ceramics studied, within the range of 0.497–0.730 W mK⁻¹ from 25 °C to 1200 °C, which indicates a promising thermal barrier material.

Thermoplastic polyurethane (TPU) is one of the elastomeric polymers which has widespread applicability in various fields. Selective laser sintering (SLS) technology is gradually being used to manufacture actual end-use components and enables novel applications (footwear, healthcare mattresses, cable and wire) for TPU. This work aims to explore an optimum protocol (laser power, scanning speed and layer thickness) for SLS fabricated TPU components, and to evaluate the processability of TPU powder through systematically analyzing the morphological properties, structure, melting temperature, crystallization characteristics and tensile properties under different processing parameters. The optimum SLS processing parameters for TPU are laser speed of 3500 mm s⁻¹, laser power of 25 W and layer thickness of 0.1 mm. The tensile strength and superlative toughness of SLS-fabricated TPU samples can reach up to 20.02 MPa and 26 631 J mm⁻³, respectively. The tensile strength of optimized SLS specimens (parameters: 20 W, 4500 mm s⁻¹, 0.15 mm) has been increased by 87.1% compared to that of reference.

To obtain the energy-saving and environment-friendly lightweight bio-based thermal insulation, polyurethane matrix was incorporated with wood fiber, bamboo fiber, rice husk and liquefied polyol at different percentages (25%, 30%, and 35%). The results revealed that the apparent density for the natural fibers reinforced thermal polyurethane insulation was between 105 kg.m⁻³ and 178 kg.m⁻³ by adding 35% of the fibers into the polyurethane matrix. The thermal conductivity of the bio-based thermal insulation ranged from 0.045 to 0.065 W.m⁻¹K⁻¹, the addition of the natural fibers increased mechanical strength. The prepared bio-based insulation showed great potential for building thermal insulations with particularly low thermal conductivity (less than 0.065 W.m⁻¹K⁻¹) and self-bearing strength.

To investigate the influence of boric anhydride (B₂O₃) on mechanical properties of nylon 6, tensile, hardness and impact test were carried out. Average tensile strength along with percentage elongation and modulus of elasticity has been calculated and plotted in this paper. Rockwell hardness and Izod impact tests were carried out to identify the hardness and toughness of materials. Boric anhydride used in this research was limited to less than 10 wt% of nylon 6 matrix material and was 2 wt%, 4 wt% and 8 wt%. Abrasion resistance of pure nylon 6 and composites was measured as weight loss due to abrasion. For the characterization of nylon 6 and its composites, Thermo-gravimetric analysis (TGA) and x-ray diffraction (XRD) were carried out. In results, it was found that the boric anhydride reinforcement increased the tensile strength and abrasion resistance when used up to 2 wt% in the nylon 6 matrix. Hardness found to be continually increased as the boric anhydride reinforcement percentage increased. The crystallinity of nylon 6 was little affected due to fillers and was found minimum for the 4 wt% boric anhydride reinforced nylon 6 composites. It was also found that the elastic modulus, Rockwell hardness and tensile strength, abrasion resistance show good correlations which are discussed in the discussion section.

Conductive hydrogels (CHs) have attracted significant attention in wearable equipment and soft sensors due to their high flexibility and conductivity. However, CHs with high-strength and free-structure still need to be further explored. Herein, 3D printing high-strength conductive polymer hydrogels (CPHs) based on a double network was prepared. Firstly, PHEA-PSS hydrogels were prepared by copolymerizing 2-Hydroxyethyl acrylate (HEA) with 4-Vinylbenzenesulfonic acid (SSS) using a photo-curing 3D printer. Then 3, 4-Ethylenedioxythiophene (EDOT) was in situ polymerized in the network of PHEA-PSS to obtain the PHEA-PSS/PEDOT hydrogels. It can not only satisfy the printing of complex spatial structures, but also has high mechanical and electrical properties. When the content of EDOT is 12 wt%, the tensile strength of the PHEA-PSS/PEDOT hydrogels is close to 8 MPa, the electrical conductivity reach to 1.2 S cm⁻¹ and the elasticity remain unchanged. Due to the presence of hydrogen and coordination bonds, CPHs have certain self-heal ability. In addition, the resistance of the hydrogel is sensitive to the changes of external pressure. The results show that CPHs can be used as a 3D printing material for flexible sensors.

A controlled release system of Plai (Zingiber cassumunar Roxb.) oil based on electrospun poly(lactic) acid (PLA) nanofiber mat was successfully developed. The physicochemical properties of the nanofibers loaded with select amounts of oil (15%, 20%, and 30% wt) were characterized using various techniques, including a morphological study using scanning electron microscopy (SEM), structural determination using Fourier transform infrared spectrometry (FTIR) and x-ray diffraction (XRD), as well as thermal properties study using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The loading content and the entrapment efficiency of Plai oil within the fiber mats were evaluated and were found to be remarkably high, ensuring that PLA was an appropriate material for Plai oil loading. The ability of the nanofiber mats to release (E)-1-(3,4-dimethoxyphenyl) butadiene (DMPBD) was also examined and the fiber mats showed controlled release characteristics. As the nanofiber mats have particularly high specific surface area with fully accessible and interconnected pore structures, a liquid medium with active ingredients will not be trapped in blind pores but can be fully released out of the fiber matrix. Furthermore, in vitro skin permeation of the active compound as well as a skin irritation were assessed using reconstructed human epidermis (EpiSkin^TM). It was found that DMPBD could efficiently penetrate through the skin model. Moreover, the nanofiber mats containing Plai oil also showed no skin irritation, indicating them as promising prototypes for medical applications.

Because fibres are difficult to disperse evenly in cement-based materials, we attempted to grow carbon nanofibers (CNFs) in situ on Portland cement clinker particles using chemical vapor deposition (CVD). The results show that the phase compositions and alite polymorph didn't change for the Portland cement clinker treated at 600 °C in the atmosphere of blended gas containing argon (Ar), hydrogen (H₂) and acetylene (C₂H₂). The CNFs was successfully grown in situ on the Portland cement clinker due to the reaction of C₂H₂ in the presence of H₂. The diameter and length of the CNFs were 20–30 nm and 0.6–0.9 μm respectively. C₃S is the main component of cement clinker. The hydration of C₃S plays a crucial role in the performance of cementitious composites. The hydration of C₃S was significantly delayed and reduced due to the incorporation of CNFs.

Macromolecules incorporating N-halamines have shown significant antibacterial properties and can be regenerated by chlorination. In this work, a new type of regenerable material made of nano-sized latex particles having N-H groups was prepared via the emulsion polymerization of methacrylamide and dodecafluoroheptyl methacrylate with divinylbenzene as a crosslinker. The N-H moieties in this polymer were subsequently transformed into N-Cl groups by chlorination with an aqueous sodium hypochlorite solution, and films were prepared by casting on substrates previously coated with a self-adhesive silicone rubber. The nanoparticles and the films were characterized by Fourier transform infrared (FTIR) spectroscopy, x-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), contact angle measurements, scanning electron microscopy (SEM) and microbiological tests. The results showed that F and Cl were successfully incorporated in the nanoparticles, that the films were thermally stable and hydrophobic (with a contact angle of 152°), and that these materials exhibited antimicrobial properties. The N-Cl groups killed bacteria by releasing active chlorine as they transitioned to N-H groups, and could be re-chlorinated with a methanol solution of isocyanuric chloride. FTIR and XPS analyses confirmed this regeneration, while SEM image showed that the morphology of the original microspheres was maintained after re-chlorination. The re-chlorinated films also maintained superhydrophobic and bactericidal characteristics.

Silicone rubber foam (SiF) with EG/HPCTP was prepared by high-temperature vulcanization. The flame retardancy of SiF was evaluated using the LOI (limiting oxygen index), UL-94, cone calorimetry test (CCT), thermogravimetric analysis (TGA), and mechanical properties. The results showed that EG/HPCTP could improve the LOI of SiF, and the SiF could pass the UL-94 V-0 rating. Compared with pristine SiF, EG/HPCTP could reduce the total heat release rate (THR), heat release rate (PHRR). Digital images of the char residues showed that the HPCTP was beneficial to promote the strength of SiF with EG. TGA showed that the branched decomposition temperature and main chain pyrolysis temperature of SiF were delayed. Mechanical properties analysis showed that EG and HPCTP could improve the mechanical properties of SiF. These indicated that the addition of EG/HPCTP was a good approach to prepare high effective flame-retarding SiF.

Utilizing renewable resources and accelerating thermal stabilization have been two main effective technical means to reduce the cost of poly(acrylonitrile) (PAN) based carbon fibre (CF). In this work, cross-linked poplar lignin (CPPL) with higher carbon content and 15 times the weight-average molecular weight of poplar lignin (PPL) was formed by doping boron phosphate (BP) in situ composites, which was blended with poly(acrylonitrile-co-vinyl acetate) (PANVA) to prepare a low-cost partially bio-based composite PANVA/CPPL-BP. During thermal stabilization, the C1s curve-fitting of x-ray photoelectron spectroscopy (XPS) spectra showed that the conjugated ladder structure of PANVA/CPPL-BP started to form at 230 °C, which was 20 °C lower than PANVA. And the acceleration in forming conjugated ladder structures was further confirmed by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric (TG), and TG-FTIR. During simulated low-temperature carbonization for composites stabilized at 230 °C in advance, the addition of CPPL-BP greatly improved the order of graphitic structure for PANVA. The mechanical property of CF mats has also been obviously improved by CPPL-BP. The possible mechanism that CPPL-BP accelerating the formation of conjugated ladder structures for PANVA/CPPL-BP during thermal stabilization was proposed. With such improvement on accelerating thermal stabilization and utilizing cheap bio-material at the same time, this PANVA/CPPL-BP composite has a great potential in developing low-cost CF.

Flexural properties calculation helps in designing structural elements like beam, cantilever and shafts. Moreover, the flexural properties are of vital importance in engineering and industrial applications such as joints replacements. The purpose of this investigation is to study for the first time, how the friction stir processing (FSP) parameters affects the flexural properties of UHMW-PE composites reinforced with nano particles. The tool rotational speed (ψ), tool feed rate (ƒ), volume percentage (ν) of nano powder and tool shoulder temperature (τ) are selected as the process parameters. The ultimate flexural strength (UFS) and flexural yield strength (FYS) are calculated from the flexural test stress-strain diagrams. The analysis of variance is conducted which reveals that the selected parameters are significant for both UFS and FYS. Macroscopic and microscopic study shows that the FSP parameters affects the mixing of the strengthening particles and hence the flexural properties of the composite. The combinations of low level of ν with medium level values of other parameters results in the highest flexural properties. Moreover, the combinations of higher levels of τ and ψ results in material degradation. At the end, optimum conditions for the highest flexural properties are sorted out and the effect of increasing the number of passes has been investigated which significantly improve the flexural properties of the composite material.

The present study deals with the ecofriendly one-pot synthesis and stabilization of silver nanoparticles (AgNPs) by using aqueous extract of Mentha longifolia branches. Spectrophotometric analysis of different ratios of reactants revealed that a 1 to 9 ratio of plant extract and silver salt solution respectively is the most suitable proportion for synthesis. Synthesis of AgNPs was confirmed initially by the observation of change in the color of the reaction mixture which was carried out at 60 °C by using 3 mM of silver salt and the pH of the reaction medium was maintained at 5.22. A characteristic surface plasmon resonance (SPR) band was observed at 495 nm of light wavelength. SEM images revealed that the nanoparticles are in ∼20–80 nm and are anisotropic and nearly spherical while EDX analysis showed the presence of elemental Ag with ∼90% signal intensity. Size distribution analysis of AgNPs was performed by dynamic light scattering technique and AgNPs were found in the range of ∼8–30 nm. ROS quantification revealed that the AgNPs have a quantum yield of 0.09 Φ which provides them the ability to proteolytically treat cancer and other microbial pathogenic cells. AgNPs did not report any photothermal activity to be used as photodynamic agents. These findings explain the redox potential of M. longifolia to bio-fabricate AgNPs and their abilities to generate ROS may help to curb dreading diseases.

This study aimed to compare the effect of thickness and background on the color changes of CAD/CAM materials (zirconia-reinforced lithium silicate (Suprinity), lithium disilicate (IPS E-max CAD), and hybrid ceramic (Enamic)). Twelve specimens for each thickness (0.4 mm, 0.5 mm, 1 mm, 1.5 mm, and 2 mm) were obtained by sectioning three CAD/CAM materials. A spectrophotometer was used to measure the color change of the specimens against different backgrounds (A2 enamel, A4 dentin, gray, and metal) using the CIELab color space system. Analysis of variance, sample t-test, and posthoc multiple comparison tests were used to evaluate and compare the color changes for different material types, thicknesses, and background colors, with a significance level of P ≤ 0.05. The result demonstrated that material type, the thickness of the material, and the color of the background had a significant effect on ΔE (P = 0.000). Regardless of the material thickness, Suprinity had the highest mean ΔE values (5.4 ± 1.9), and E-max had the lowest mean ΔE values (1.1 ± 0.6). At 2 mm thickness, Enamic presented the lowest ∆E values (0.5 ± 0.5) against the A2 background. The 0.5 and 1 mm specimens corresponded to the highest ΔE values, whereas the 1.5 and 2 mm thickness specimens predominantly gave the lowest ΔE values. All the independent factors, including the type and thickness of the material, and color of the background, contributed significantly to ΔE of the tested materials (P ≤ 0.05). The study confirms the high masking ability of the lithium disilicate (E-max) material. In clinical situations where the color of the core needs to be masked, it is recommended to use lithium disilicate (E-max).

Rolled Zn-0.8Li-0.2Ag(wt%) alloy as candidates for biodegradable materials. The biodegradable behavior of Zn-0.8Li-0.2Ag alloy in different solutions (Ringer's, DMEM, SBF and DMEMp) was investigated. The cytotoxicity of Zn-0.8Li-0.2Ag alloy and its antibacterial properties against staphylococcus aureus, enterobacter faecalis and candida albicans were evaluated. The results showed that Zn-0.8Li-0.2Ag alloy consists of zinc matrix and a LiZn₄ secondary phase. The presence of Cl⁻ causes locally corroded of Zn-0.8Li-0.2Ag alloy in Ringer's solution, and its corrosion resistance is lower than that of the alloy which is uniformly corroded in other solutions containing CO₃²⁻ and PO₄³⁻. Zn-0.8Li-0.2Ag alloy is non-toxic and exhibits better antibacterial properties than the experimental reference group without silver.

Understanding the biomechanical behavior of dentin hard tissue with fluid-filled dentin tubules and hydrated matrices is essential for studying this functionally graded biological composite. The stereo-digital image correlation technique with an adaptive high-magnification field of view (FOV) for fully hydrated biological tissue measurement was investigated. The adaptive magnification is controlled by the length of extension tubes. To determine both the unbound water loss induced and load-induced three-dimensional (3D) deformation of dentin hard tissue from a fully hydrated state to a non-hydrated condition, samples of dentin blocks and half teeth in sagittal sections were studied for a period of 2 h in situ over varied speckle patterns. The effects of speckles on water evaporation, camera pre-heating, and measurement accuracy in the wet, curved and long-term measurement were analyzed. The elastic modulus and Poisson's ratio of both dentin and pulp in response to unbound water evaporation were measured. With the unbound water loss, the mean values of the elastic modulus generally increased from ∼8 GPa to ∼10 GPa in pulp region and from ∼10 GPa to ∼12 GPa in dentin region. The mean values of the Poisson's ratio increased both in pulp and in dentin. Poisson's ratio in the dentin regions (∼0.3) were generally smaller than those in the pulp regions (even can reach 0.6), irrespective of the partial dehydration time. Further analysis of the full-field deformation results provided insight into the unbound water-induced regional deformations and mechanical changes in human dentin. It's found that the unbound water loss induced deformations were more prominent when compared to load induced deformations.

The present work attempts to utilize iron tailings as the main raw materials for preparation of functional ceramics as a means of resource utilization. A new type of endothermic functional ceramics, which can be used in the field of solar energy, was prepared via semi-dry pressing followed by pressureless sintering. The results show that the functional ceramics made of 68 wt% iron tailings, 26 wt% iron ore, 3 wt% alumina, 1 wt% potash feldspar and 2 wt% kaolin, sintered at 1185 °C exhibited the best overall performance. Visual observation reveals that there were no cracks on the surface of the samples even after 20 cycles of intense thermal shock. Other attributes could be summarized as follows: Infrared emissivity in mid-infrared region: 0.85; thermal conductivity at 500 °C: 2.066 W/(m·K); flexural strength: 119.03 MPa. XRD analysis indicates that the main crystalline phases in the samples are augite, magnetite and a small amount of hematite. An increase in the proportion of iron oxide contributed to lower melting temperature of the functional ceramics, deepen color, promote densification and increase infrared emissivity. In short, the introduction of iron tailings improves the thermal and physical properties to a certain extent.

We search for homovalent alternatives for A, B, and X-ions in ABX₃ type inorganic halide perovskites suitable for tandem solar cell applications. We replace the conventional A-site organic cation CH₃NH₃, by 3 inorganic cations, Cs, K, and Rb, and the B site consists of metals; Cd, Hg, Ge, Pb, and Sn This work is built on our previous high throughput screening of hybrid perovskite materials (Kar et al 2018 J. Chem. Phys.149, 214701). By performing a systematic screening study using Density Functional Theory (DFT) methods, we found 11 suitable candidates; 2 Cs-based, 3 K-based and 6 Rb-based that are suitable for tandem solar cell applications.

Full-Heusler compounds have three crystal structures with a different order degree; the highly ordered L2₁, partially disordered B2, and completely disordered A2 structures. To reveal the effects of the order degree on thermoelectric (TE) properties of the full-Heusler compounds, Mn₂VAl samples with varied L2₁ and B2 order degrees are prepared by changing preparation conditions, and their Seebeck coefficients and electrical conductivities are measured in a wide temperature range. As the B2 order degree becomes higher, the Seebeck coefficient increases, leading to the increase of the power factor (PF). The maximum PF is 2.84 × 10⁻⁴ Wm⁻¹ K⁻² at 767 K for the Mn₂VAl sample with the highest B2 order degree. This study demonstrates that the TE properties of Mn₂VAl can be enhanced by increasing the fraction of the B2 phase. A relation between the Seebeck coefficient and crystal structures is also discussed based on the calculation of the electronic density of states of Mn₂VAl with the L2₁ and B2 structures.

In this work, we report simultaneous electrochemical exfoliation of graphite powder using SDS, anionic surfactant salts, and cyclic potential to prepare graphene on carbon paper. Then, Nickel is electro-reduced into graphene nanosheets on carbon paper and also on the bare carbon paper to use in alkaline media for hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR). Afterward, graphene and Ni-graphene are characterized using scanning electron microscopy, atomic force microscopy (AFM) and electrochemical technique. SEM images show the Cauliflower structure of Ni in the absence of graphene and nanoparticle shapeless in the presence of smooth graphene. The electrochemical results show an excellent catalytic activity of Ni-graphene/ carbon paper with an over potential of 90 mV (Versus Ag/AgCl), which is lower than the literature value for Ni in alkaline electrolyte for HER (120 mV dec⁻¹). The effect of graphene support on the electrochemical impedance spectroscopy response, activation energy and HER activity of the samples are investigated carefully. Finally, we prepare a novel gas diffusion electrode by using Ni pasted on carbon paper for the ORR in fuel cells and compared it with standard Pt/C catalysts using linear sweep voltammetry.

Lotus leaf porous carbon (LLPC) prepared from waste lotus leaves has a large specific surface area (2440 m² g⁻¹), and is used for the adsorption of rhodamine B (RhB) from wastewater in this study. The effects of different parameters such as LLPC dose, initial pH of wastewater, adsorption time, initial RhB concentration, and temperature on adsorption have been systematically explored. Notably, 100% removal efficiency of RhB (60 ppm) is obtained at a low LLPC concentration of 0.125 g l⁻¹. The adsorption equilibrium with a maximum theoretical adsorption capacity of 718.9 mg g⁻¹ at 313 K is described by the Langmuir isotherm. The results for removal efficiency as a function of time are consistent with the pseudo second-order kinetic model and the adsorption process is dominated by chemisorption. Thermodynamic studies confirm that RhB absorption by LLPC is spontaneous at 313 K. The experiments conducted to determine the adsorption mechanism show that intraparticle diffusion is not the only rate-limiting step during adsorption, and the boundary effect becomes more dominant with an increase in adsorption time. The excellent RhB adsorption performance of LLPC and adsorption mechanism afford novel insights into this process for the application of biomass materials in wastewater treatment.

This work tries to synthesize ZSM-5 zeolite using fly ash (FA) by hydrothermal method and study the adsorption effect of the zeolite on phenol, quinoline and indole in aqueous solution. The zeolites were characterized with x-ray diffraction (XRD), scanning electron microscopy (SEM), x-ray fluorescence (XRF), fourier transformation infrared (FTIR) and N₂ adsorption-desorption isotherm. The characterization results showed that HZSM-5 zeolite was successfully synthesized. The higher mass ratio of sodium carbonate to fly ash during melting is beneficial to improve the purity of ZSM-5 zeolite and its removal rate of organic matters. These results have been confirmed by XRD and principal component analysis (PCA). The adsorption process of phenol, quinoline and indole in aqueous can be well described with the double exponential kinetic model. The adsorption capacity of ZSM-5 zeolite for phenol, quinoline and indoles can be up to 24.41 mg g⁻¹, 35.99 mg l⁻¹ and 34.05 mg g⁻¹ respectively, and the removal rates can reach up to 82.80%, 84.86% and 83.20% respectively. The optimal pH value for adsorption ranges from 5 to 7.

The current work investigates the adsorption behavior of methylene blue (MB) from aqueous solution using natural Saudi Red Clay (SRC) adsorbent. The surface characteristics of the adsorbent were investigated using surface area measurements (S_BET), Scanning Electron Microscopy (SEM), X-ray florescence (XRF) and Fourier-Transform Infrared Spectroscopy (FTIR) and x-ray diffraction (XRD). Various process parameters such as pH, adsorbent dosage, initial dye concentration, contact time and temperature were investigated. MB removal efficiency was noticed to increase with increasing adsorbent dosage while the effect of pH was noticed to be insignificant for the pH range studied. Applying the Langmuir isotherm fitting to the experimental data, a maximum adsorption capacity was found to be 50.25 mg g⁻¹ of clay at 298 K. Pseudo-first-order and pseudo-second-order models were applied to the experimental data to study the kinetics of the process. Pseudo-second-order model fitted well with the experimental as compared to the pseudo-first order model. The spontaneous and endothermic nature of the adsorption process was revealed by studying the thermodynamic parameters of the system. The positive ΔS° value indicates the affinity of MB molecules to the adsorbent surface. Re-usability/recycling study showed that this material can be successfully reused at least four times in this study without significant loss in the adsorption capabilities.

The metakaolin-based porous geopolymer were prepared by emulsion templating method with sunflower oil as the template agent. The effects of the type of emulsifiers with different ionic properties, including sodium stearate (SS), polyacrylamide (PAM), and cetyltrimethylammonium bromide (CTAB), which are respectively belonging to anionic, nonionic and cationic emulsifiers, on the paste viscosity, mechanical strength and pore structure of geopolymer were studied. Fourier transform infrared spectroscopy (FTIR) was used to characterize the influence of emulsion template on the geopolymerization. Scanning electron microscope (SEM) and Image-Pro Plus (IPP) software were used to examine the pore structure of geopolymers, including pore size distribution, average size and roundness of pores. Results indicate that geopolymerization is not significantly affected by the incorporation of emulsion template, while the average size, shape and connectivity of pores in geopolymer were significantly influenced by the type of emulsifiers. With the addition of SS, PAM, and CTAB, the average pore size were 18.1, 27.4, and 11.7 μm, respectively, while the control is 18.9 μm. Both the shape regularity and open porosity of pores were increased with SS and PAM, while no significant changes with CTAB. It is promising to make geopolymer with controllable macro pore structure by adjusting the types of emulsifiers in emulsion templating method by adjusting the oil-water interfacial tension and the particle dispersion.

Observation of ferromagnetic and granular superconductive features in highly-oriented-pyrolytic-graphite (HOPG) has recently attracted an important attention. We report a novel temperature dependent XRD and SQUID investigation of HOPG in the temperature range from 300.15 to 77.15 K. Unusual hysteresis features indicate the possible presence of vortex states in conditions of magnetic field approximately perpendicular to the HOPG layers. This interpretation is further supported by additional measurements performed on intermediate lamellae extracted by exfoliation. Evidence of a possible structural-transition in the c-axis of HOPG in the temperature range between 77 K and 100K is also provided by using the Rietveld refinement method. ZFC and FC measurements performed at high field values of 5000–10000 Oe, together with mFC-mZFC subtraction, highlight absence of a sharp depletion of the difference between magnetization signals towards zero. These observations may indicate the possible presence of additional unsaturated weak features, which are ascribed to superconductive signals as previously predicted by Scheike et al (Scheike et al 2013 Carbon; 59:140).

A number of past studies have focused on point and line defects in graphene epitaxially grown on SiC substrates. However, few studies have investigated closed-ring defects formed within grain boundary loops. The present study addresses this issue by applying low-temperature scanning tunneling microscopy/spectroscopy to investigate the atomic structures of closed-ring defects in graphene epitaxially grown on 4H-SiC, and to evaluate their effects on the electron state density. The results indicate that the orientations of the graphene lattice inside and outside of grain boundary loop structures are rotated uniformly by an angle of 30° relative to each other, suggesting that closed-ring defects are highly ordered and are mainly composed of clusters of pentagon-heptagon carbon rings and highly ordered pentagon-heptagon chains. In addition, the spectroscopy results reveal for the first time that the density of electron states inside a closed-ring defect is strongly localized and position-dependent. Moreover, these closed-ring defects can eliminate intervalley scattering while maintaining intravalley scattering. These findings are not only helpful for contributing to a deeper understanding of the effects of closed-ring defects in graphene, but also present a potentially useful valley-filtering mechanism for charge carries that can be applied to the practical development of all-electric valley-based devices.

A key challenge in the fabrication of ferromagnetically filled multilayer fullerenes (carbon nano-onions, CNOs) is the manipulation of the structure, composition and electronic band characteristics of both the carbon layers and encapsulated ferromagnetic material. Interestingly, a recent work has demonstrated that the addition of small quantities of water during the chemical vapour synthesis of Fe₃C filled CNOs can allow the local manipulation of the Fe₃C crystal-structure and induce the nucleation of a novel high pressure Bbmm Fe₃O₄ crystal-phase. In this report we propose an advanced study of such structural transition. Particularly, we investigate the morphological, optical (band-gap) characteristics and magnetic properties of the as produced CNO materials by using transmission electron microscopy, vibrating sample magnetometry, x-ray photoelectron spectroscopy and UV–vis spectroscopy.

The samples of stoichiometry Pb(Zr_0.35−xMn_xTi_0.65)O₃, x = 0.00, 0.02, 0.06, 0.10 (PZMT) were synthesized by solid state reaction route. For the first time, 35/65 lead zirconate titanate ceramics were modified by manganese (Mn) by replacing zirconium. X-ray diffraction (XRD) study has confirmed the formation of tetragonal phase in samples and no structural change has been observed due to Mn doping. Results of scanning electron microscopy (SEM) showed polycrystalline nature through shape, size and grain distribution in microstructures of all samples. At room temperature, the samples have shown identical nature in variation of dielectric constant (_r) and tangent loss (tanδ) with frequency. At 50 kHz frequency, the value of maximum dielectric constant (_max) has been changed from 5440 to 12 562 due to Mn. With increase in doping amount of Mn, the values of Curie temperature (T_c) have been decreased from 435 to 373 °C. ${Tan}\delta$ of samples is decreased with increase in the dopant concentration. The diffusivity of PZT has increased with 2% of Mn doping. But further increase in the Mn concentration has decreased the diffusiveness of the samples.

The aim of the study was to obtain a smart textile material with shape memory alloys. NiMn-based shape memory alloy was produced by arc melting system for this purpose. Phase transition temperatures of the fabricated alloy were determined by using differential scanning calorimeter (DSC). The crystallographic structure of the fabricated alloy was characterized by x-ray diffractometer (XRD). The fabricated shape memory alloy was converted to the particle form and filled into polymer matrix to obtain shape memory effect of this polymeric composite material. Polymeric composites (PCs) were produced in film form and shape training of PCs were studied under different conditions. The shape memory behavior of samples was investigated into the water for fast response during applying heat. Damping capacity of composites was measured by using dynamic mechanical analyzer (DMA) according to temperature rising. The shape recovery was observed under certain stimuli on the SMA filled polymeric composites.

In this paper, micro-mechanics of shape memory alloys (SMA) is investigated for design of smart structure and devices, based upon three dimensional constitutive model. In this work, a micro-mechanics based approach is presented. A modification in temperature field of the above model is proposed, where temperature is taken as function of time. Thermal parameters corresponding to transformation temperatures are introduced here. The model solution is presented for the of a set of initial and boundary conditions based upon any type of thermal parameters. Three particular cases for different thermal and structural loading-stresses are presented here. The solution given here expresses the response of smart dampers for various thermal and structural loading conditions. Moreover, the applications of this system were also investigated.

The present paper addresses developing the Dynamic Stiffness Method (DSM) for natural frequency analysis of functionally graded beam with piezoelectric patch based on the Timoshenko beam theory and power law of material grading. Governing equations and general solution of free vibration are conducted for the beam element with piezoelectric layer that is modelled as a homogeneous Timoshenko beam. The obtained solution allows establishing dynamic stiffness matrix for modal analysis of FGM beam with bonded piezoelectric distributed sensors/actuators. Effect of thickness and position of the smart sensors/actuators and material parameters on natural frequencies is studied with the aim for dynamic testing and health monitoring of FGM structures. The theoretical developments are validated and illustrated by numerical examples.

Switching plasmonic resonance modes in metamaterials have drawn enormous attention in recent years due to its great potential in applications in electromagnetic modulation and sensing. The switching process is essentially dependent on the connection way in the gaps of the metamaterial structure. In this work, we experimentally investigate the resonance switching effect in a multi-gap metamaterial structure at terahertz frequencies. It is found that a new inductor-capacitor circuit (LC) resonance would generate if the center gaps are totally connected. By decomposing the types of the connection in the center gaps, it is found that under horizontally polarized incidences, such switching effect is attributed to the horizontal connection (HC), while the vertical connection (VC) cannot bring any change in the transmission. This characteristic is further theoretically generalized to an active modulator by replacing the metallic HC to vanadium dioxide (VO₂) HC, where the dynamic switching effect is observed. The detail study in the resonance switching effect may broaden the avenues toward the control of terahertz waves and the development of modulators and sensors in the terahertz band.

The concentration and cloaking phenomena of physical fields in Metamaterials has captured the attention of the researchers due to their simplified approaches. However most of the work conducted is focussed on controlling single physical field. Transformation optics has paved the way for developing intelligent bifunctional devices. Bifunctional devices are such controlled devices which execute two different physical functions simultaneously and independently. In this work we have applied the transformation optics theory to design a multilayered two dimensional spherical bifunctional device which behaves like an electric concentrator and thermal invisibility cloak simultaneously. Moreover, we have also observed the normalized behavior of the proposed device. The simulation performance confirms the feasibility of our suggested model.

In this paper, the ZnO–SiO₂ was synthesized using ZnO nanopowders and SiO₂ developed from coconut husk ash by using conventional solid state method. The ZnO–SiO₂ crystal system was heat-treated and the properties was studied. The XRD results showed high intensity peaks due to its high crystallinity when sintered at high temperature. The morphological differences can also be observed through FESEM images as the heat-treated crystal system showed well-distinct boundaries. Meanwhile, the absorbance intensity decreased and shifted to the lower wavelength after heat-treated. The optical band gap value of the ZnO–SiO₂ was 3.22 eV before treated and increased to 4.05 eV after heat treated. The presented results showed good properties of zinc silicate and it has a great potential as phosphors in optical application.

GaSb crystal ingots were grown with vertical Bridgman method. The effects of temperature gradient on the structure and properties of GaSb crystals were investigated. When the temperature gradient increased from 5 to 7 °C cm⁻¹, the crystallinity of the ingot improved, the dislocation density decreased by 55%, from 3928 to 1785 cm⁻²; the carrier mobility increased by 29.6%, from 868 to 1125 cm² V⁻¹ · s⁻¹; the resistivity decreased 50.6%, from 12.45 to 6.332 × 10^–3 Ω · cm; the infrared transmission increased from 27% to 32%. When the temperature gradient increased from to 7 to 9 °C cm⁻¹, the crystallinity of the ingot deteriorated obviously, the dislocation density increased 4.38 times, from 3928 to 9609 cm⁻²; the carrier mobility decreased by 52.4%, from 1125 to 738 cm² V⁻¹ · s⁻¹; the resistivity increased 6.2 times, from 6.332 to 23.94 × 10^–3 Ω · cm; the infrared transmission decreased from 32% to 25%.

This study reports the fabrication of n-type aluminum- and yttrium-codoped zinc oxide (AZOY) on n-Si (AZOY/n-Si) heterojunction solar cells (HJSCs) by using RF magnetron sputtering at various working pressure. AZOY thin films deposited on glass and n-Si substrates at various working pressure were evaluated for optoelectrical properties and performance. At a working pressure of 3 mTorr, the AZOY films showed the lowest resistivity of 8.11 × 10^–3 Ωcm and visible transmittance (400–800 nm) of 84.64%, and AZOY/n-Si HJSCs achieved a high conversion efficiency of 11.83% (V_oc: 498 mV, J_sc: 35.89 mAcm⁻², and FF: 0.662). Repeating the optimal working pressure, the n-Si substrate was immersed in ammonium fluoride (NH₄F) solution to improve the AZOY/n-Si interface state. The fluorine atom had the strongest electron negativity for effective passivation of the silicon dangling bond, and the device's performance was able to further increase conversion efficiency to 12.64% (V_oc: 523mV, J_sc: 36.79 mAcm⁻², and FF: 0.657). Moreover, NH₄F solution treatment of the silicon surface can increase the thinness of the SiO_x layer from 1.27 to 0.79 nm and reduce the interface state density from 8.59 × 10¹¹ to 1.13 × 10¹¹ cm².

We study electronic and optical properties of zincblende GaN doped with various Cr concentrations (3.12%, 6.25%, 9.37%). We conduct the calculations by employing DFT + U in Wien2K code while supercell size (1 × 2 × 2) is kept fixed for all cases. Electronic properties are changed with effect of dopant where 3d levels of dopant and 2p level of N produce p-d hybridization and this hybridization is highly affected by increasing impurity contents. Absorption spectra are blue shifted upon increase in dopant contents and absorption peaks are more pronounced in UV region. Refractive index and dielectric constant shows decrease as Cr concentration increases. Results reported in study indicate that Cr:GaN material may be considered a potential candidate for fabrication of optoelectronic, photonic and spintronic devices.

Nuclear magnetic resonance (NMR) magnets generally need an extremely uniform magnetic field in the space where the specimens will be placed. Although high temperature superconducting bulk magnets can obtain an intense magnetic field of more than 3 T, the field distribution is intrinsically characterized to be inhomogeneous, showing steep gradient. Aiming at the practical application of compact and portable NMR magnets, the authors have developed magnet systems capable of generating uniform magnetic fields in a narrow space between face-to-face settled magnetic poles, targeting to obtain a uniform magnetic field between the poles. Here, the authors modified the shape of magnetic field distribution from convex to concave by attaching a ferromagnetic iron plate on one of the pole surfaces, and then settled them face to face with a gap of 70 mm. The uniformity of the magnetic field in the x-y plane was experimentally measured and estimated along various z-axis directions. The best uniformity of 463 ppm at 1.25 T was obtained in the experimental evaluation in the x-y plane of 4 × 4 mm² at z = 0.5 mm from the iron plate surface. The value of uniformity along the z-direction range was extended from 0.8 mm to a depth of 1.1 mm. These results show that the possible space of NMR signal detection or the available sample size can be enlarged.

The Y_1-xNi_xBa₂Cu₃O_7-δ superconducting samples with low level of Ni concentration were prepared by the standard solid-state reaction. The AC susceptibility, magnetoresistivity, microstructure and the critical current density, J_c, of samples as a function of temperature, magnetic field and Ni doping are investigated. The AC susceptibility measurements show that the displacement of the peak temperature T_p of the imaginary part of the susceptibility χ'' versus magnetic field was reduced strongly by Ni doping up to an optimum level, which shows the increasing of flux pinning by Ni doping. The J_c of samples was derived from AC susceptibility utilizing the Bean model. It shows an increasing in J_c by Ni doping, at any temperature or magnetic field, consistent with the results of J_c measurements. The magnetoresistance measurements were carried out under magnetic fields up to 1 T and explained by TAFC model. Utilizing this model, the vortex dynamic behaviour and the activation energy U (H) of the compound are investigated. We found that the U (H) increases and the resistive broadening is strongly reduced by Ni doping. The SEM measurements show that the grain sizes are clearly increased and the grain connections are improved by Ni doping. The results of all the observations taken from different measurements are consistent together and indicate the Ni doping has an effective role to improve the intergranular coupling and flux pinning.

We are now developing a new in situ deposition process for MgB₂ film as a candidate method to mass-produce MgB₂ thin film superconducting tape. In the new method, a MgB₂ film is deposited on a heated metal substrate by a hybrid deposition method, which consists of thermal evaporation of magnesium and sputtering of boron. By using the hybrid deposition method, the substrate temperature can raise from 250 to 350 °C, while its fluctuation is kept less than 1 °C, which will improve the quality and reproducibility of MgB₂ film in mass production. The J_c of MgB₂ film deposited by the hybrid deposition method at 20 K and self-field was more than 30,000 A mm⁻², which was better than the results reported by the two-step in situ process using DC sputtering and 830 °C high-temperature post annealing [1] or by the as-grown depostion using sputttering targets of Mg and B [2]. Although we obtained better J_c than other deposition methods that use sputtering process, the J_c is still lower than the value we obtained by using a co-evaporation method with electron beam (EB). We investigated the film structure and J_c–B–T properties of the film made by the hybrid deposition method and compared them with those of the film made by co-evaporation. From the analysis results, we think the reasons for the lower J_c are the larger amount of heterogeneous phases such as magnesium oxides in the film and the amorphous B phase under the MgB₂. We expect to improve the the crystal qualities and superconductivities of the MgB₂ film deposited by the new method by removing impurities in Ar gas during sputtering and thinning the B amorphous phase by increasing the Mg deposition rate in the initial stage of deposition.

We have investigated the electronic structure and magnetic properties of the full-Heusler alloy Co₂MnSi (CMS) under external pressures and strains. The total and individual spin and orbital magnetic moments were also obtained under pressures and strains. We found a gradual transition from half-metallic to metallic state around 31 GPa in our relativistic study. The spin polarization degree (SPD) was reduced at the Fermi level by including relativistic effect of spin–orbit coupling. The exchange energy describes the trend of decreasing SPD values. The decreasing behavior observed for individual orbital magnetic moments under applied pressures. The metallic behavior was also observed under 8% strain along [001] direction. It was shown that the SPD values decrease in the presence of spin–orbit coupling, whereas the spin magnetism of Co₂MnSi under uniaxial strain is marginally affected.

Undoped ZnO films grown on sapphire by pulsed laser deposition are magnetic at room temperature. A comprehensive study involving x-ray diffraction, positron annihilation spectroscopy, and superconducting quantum Interference device-vibrating sample magnetometer is performed to study the origin of the observed magnetization. Correlations between the saturation magnetization, V_Zn−2V_O concentration and surface to volume ratio of the grain found experimentally show that the magnetization is associated with the vacancy cluster and probably V_Zn−2V_O residing on the grain surface.

The magnetite Fe₃O₄ nanoparticles were synthesized by using chemical co-precipitation method and these nanoparticles were successfully coated by polyethylene glycol (PEG) with variation concentrations of PEG. The magnetite Fe₃O₄ nanoparticles used as a bimolecular label (nano-tags), exhibiting a soft magnetic behavior with magnetization (M_s) of 77.16 emu g⁻¹ and coercivity (H_c) of 50 Oe respectively. The polyethylene glycol (PEG) was used as a biocompatible polymer. The x-ray diffraction (XRD) patterns of the Fe₃O₄ showed that Fe₃O₄ was well crystallized. It also confirmed the existence of invers spinel. The diffraction peak of 35.4° was used to calculate the crystallite size. The estimation of Fe₃O₄ average crystallite size is 12 nm, while the PEG-coated Fe₃O₄ nanoparticles is 8.6 nm. The transmission electron microscopy (TEM) images of Fe₃O₄ showed that the morphology of magnetite Fe₃O₄ nanoparticle is spherical in shape with uniform grain size and good dispersibility despite the agglomeration it found in some place. The addition of PEG can decrease the agglomeration and reduce the particle size. The existence of PEG layer on Fe₃O₄ was confirmed by Fourier transform infrared (FTIR) spectroscopy. The result of Vibrating Sample Magnetometer (VSM) showed that saturation magnetization (M_s) of Fe₃O₄ nanoparticles decreased from 77.16 to 37.15 emu g⁻¹ with the increase of PEG weight from 0% to 50%. Such Fe₃O₄ nanoparticles with favorable size and tunable magnetic properties are promising biosensor applications.

The easiness of preparation and tailored properties of perovskite nanoparticles rendered them an important class of materials in the last decade. In this work, La_0.7Sr_0.3Fe_1-xM_xO₃ (M = Mn, Co and x = 0, 0.5) orthoferrites were synthesized using combustion method and examined using X-ray diffraction. The orthorhombic structure was clearly obvious with Pbnm space group without the need of any thermal treatment. Field emission scanning electron microscopy (FESEM) accompanied by Energy-dispersive spectroscopy studies were also performed, evidencing the similarity of both nominal and chemical compositions for the studied orthoferrites. The thermal dependence of the dielectric properties was investigated (from room temperature to 698 K) in the frequency range (70 Hz–5 MHz). Magnetic properties were investigated at room temperature and discussed.

Magnetic phase transitions under high pressure are reported for the diamond lattice antiferromagnet Co_3−xRh_xO₄ in the range of 0 ≤ x ≤ 2.0, which is an isostructural S = 3/2 system for the well-known frustrated antiferromagnet CoAl₂O₄. In the Co_3−xRh_xO₄ system, magnetic and specific-heat measurements at ambient pressure revealed that a second-order antiferromagnetic transition occurred at the Néel temperature (T_N) which exhibits a nonmonotonic x-variation. The physical pressure variations of T_N were determined by ac-calorimetry under hydrostatic pressures up to p = 2.6 GPa for Co₂RhO₄ and CoRh₂O₄. The rates of change of T_N with pressure (i.e., the pressure coefficients), 1.93 and 1.61 K GPa⁻¹, respectively, were comparable to those for CoAl₂O₄ and Co₃O₄, respectively. The pressure coefficients of magnetic ordering temperature for these A-site spinel compounds were considerably larger than those for other spinel and iron-garnet compounds which follow the empirical '10/3 law'. Simple analysis of the chemical and physical pressure coefficients of T_N revealed that T_N depended on both the lattice volume and the oxygen positional parameter u.

An organic-inorganic hybrid nanoparticle (HNPs) composed of Sm(TTA)₃Phen, a coordination compound, and NaY_0.78Er_0.02Yb_0.20F_4, an upconversion nanoparticles (UCNPs), has been developed and used for H₂O₂ sensing application. Herein, Sm(TTA)₃Phen absorbs ultraviolet (UV) light and gives fluorescence in yellow-red-near infrared (NIR) region. Whereas, the UCNPs absorb NIR radiations (980 nm) and consequently emit in green-red region through photon upconversion process. Two important optical phenomena are observed when HNPs are simultaneously excited with UV (266 nm) and NIR (980 nm) laser radiation- (i) an energy transfer from Sm³⁺ to Er³⁺ ions, and (ii) color tunable emission from red to green, if the power of 980 nm laser is varied. Further, the material is highly competent to sense H₂O₂ through fluorescence quenching of Sm³⁺ emission in presence of H₂O₂. The nature of quenching is conspicuously different for different concentration/volume range of H₂O₂. For lower volume range, the rate of decrease of emission/excitation intensity is linear, while for higher volume range the decay in intensity is exponential. The attained minimum detection limit for H₂O₂ is 2 μl, which is significant for sensing applications.

Lithium niobate material (LN) has shown great application potentials in the fabrication of integrated optical devices due to its excellent physical properties, especially with the occurrence of lithium niobate-on-insulator (LNOI) substrate. However, the greatest challenge of micro/nano optical devices based on LN material lies in the precise etching process and thus limits its applications. In this paper, we comprehensively analyze the etching results treated by the proposed proton-exchanged wet-etching method (PEWE) combining with theoretical simulations and experiments. It is found that the proton-exchanged layer in the LN material can be easily etched after using a mixture acid of HF/HNO₃, leading to the improvement of etching rate and surface morphology. The lowest roughness of the optical waveguide is measured to be 0.81 nm, which is beneficial for the performance improvement of LN-based optical devices. Ultimately, a quasi-vertical sidewall of the upper part of optical waveguide with improved surface morphology is successfully realized by utilizing the PEWE. Moreover, this method could also be extended to improve the performance of LNOI-based optical devices and pave the way for ultra-compact photonic integrated circuits based on LNOI.

A comparative study on the photoresponse of zinc oxide nanowires in direct-current (DC) and alternating-current (AC) domains is presented. Zinc oxide ultraviolet photodetectors exhibit positive photoconductivity in DC domain which means that the resistance decreases upon illumination. However, in the frequency domain, zinc oxide nanowires exhibit a solid frequency-modulated response to the ultraviolet illumination leading to a tunable photoconductivity. It is shown that in AC domain the photoresponse of zinc oxide nanowires can be finely adjusted from the positive photoconductivity (resistance decrement) to negative photoconductivity (resistance increment) simply by tuning the driving frequency. Frequency-modulated photoresponse of zinc oxide nanostructures provides an exclusive platform for the realization of dual-response or bipolar photoresponse ultraviolet photodetectors which could be of high technological importance. The zinc oxide nanowires exhibit a responsivity of +180 mA W⁻¹ to the ultraviolet illumination in the DC mode. The nanowires show an almost equal but negative responsivity in the AC domain. Practical implication of the bipolar ultraviolet photodetectors based on ZnO nanowires is presented.

Stretched Ag nanoparticles (AgNPs) have been obtained by photoelectric modification with room temperature. Significant elongation occurs on partial AgNPs with diameters ranging from 50 to 120 nm. For AgNPs with diameters larger than 120 nm, protuberances with sizes about 10 nm have been observed after photoelectric modification. Simulations based on finite difference time domain method have been used to reveal the process of the photoelectric modification. Such morphology changes of AgNPs can be attributed to the plasmonic phase transition and electric induced migration of Ag atoms at AgNPs surfaces. Due to the stretching of AgNPs, tunable plasmon resonances in visible spectrum have been obtained. This work could provide a new technology for the metallic nanostructure modification under low temperature.

Carbon allotropes such as diamond, nano-tube, Fullerene, and Graphene were discovered and revolutionised material sciences. These structures have unique translational and rotational symmetries, described by a crystallographic group theory, and the atoms are arranged at specific rigid positions in 3-dimensional (D) space. Regardless of these exotic molecular structures, the structures of materials are topologically trivial in a mathematical sense, that their bonds are connected without a link nor a knot. These days, the progress on the synthetic chemistry is significant to make various topologically non-trivial molecular structures. Topological molecules (0D) including Trefoil knots, a Hopf-link, a Möbius strip, and Borromean rings, were already realised. However, their potentially exotic electronic properties have not been sufficiently explored. Here, we propose a new 3D carbon allotrope, named Hopfene, which has periodic arrays of Hopf-links to knit horizontal Graphene sheets into vertical ones without connecting by σ bonds. We conducted an ab inito band structure calculation using a Density-Functional-Theory (DFT) for Hopfene, and found that it is well-described by a tight-binding model. We confirmed the original Dirac points of 2D Graphene were topologically protected upon the introduction of the Hopf links, and low-energy excitations are described by 1D, 2D, and 3D gapless Fermions.

Double-perovskite composite oxides (A₂BB'O₆) usually have excellent functional properties and are widely studied and applied. Its electrical, magnetic or other properties can be optimized by doping transition metal elements at its B or B' site. In this paper, the effects of Mn doping and testing atmosphere on the crystal structures and the electrical conductivities of Sr₂Fe_1−xMn_xNbO₆(SFMN) were systematically investigated. The experimental results demonstrate that the conductivities of SFMN will increase in air while decrease under H₂/H₂O(g) atmosphere with Mn content rise. Doping Mn can enlarge the interplanar spacing of SFMN which increases the resistance of electron conduction across the crystal. First-principles calculations and XPS analysis results reveal that the chemical adsorption of H₂ on the surface of SFMN is a key reason for its conductivity increase under H₂/H₂O(g) atmosphere. The forbidden band width of the reduced state of Sr₂FeNbO₆ (1.177 eV) is much smaller than that of the oxidation state (1.426 eV). The analysis results suggest that Fe 3d electron transition and exchange interaction between Mn–O–Mn are mainly two possible mechanisms contribute to the electrical conductivity of SFMN.

In addition to providing basic protective functions, modern military uniforms are also being designed to provide special functions, such as infrared shielding. In this study, a nanoscale copper film was deposited on Kevlar para-1414 aramid fabric by magnetron sputtering technology to significantly enhance infrared shielding. The deposition of a uniform nano-copper film on the surface of the aramid fabric enhanced infrared shielding, tensile strain, and conductivity, which is of guiding significance for the development of infrared shielding garments.

Carbon nanohorns (CNHs) are mixed with cellulose to make freestanding thin-film conductive sheets. CNHs, at different ratios (5, 10, 25, 50 wt%), form composites with cellulose (hydroxyethylcellulose). Freestanding cellulose–carbon nanohorn (CCN) sheets were fabricated using a 100 μm-thick metal bar coater. Surfactants or any other chemical treatments to tailor the surface properties of CNHs were avoided to obtain composite sheets from pristine CNHs and cellulose. Utilizing the hygroscopic property of hydroxyethylcellulose and the electrical conductivity of CNHs paved a path to perform this experiment. The synthesis technique is simple, and the fabrication and drying of the sheets were effortless. As the loading concentration of CNH increased, the resistance, flexibility, and strength of the CCN composite sheets decreased. The maximum loading concentration possible to obtain a freestanding CCN sheet is 50 wt%. The resistance of the maximum loading concentration of CNH was 53 kΩ. The response of the CCN sheets to water vapor was 4 s and recover time was 13 s, and it is feasible to obtain a response for different concentrations of water vapor. High-resolution transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, resistance measurement, tensile strength measurement, and thermogravimetric analysis were used to investigate the mechanical, morphological, electrical, and chemical properties of the CCN sheets.

Nickel oxide (NiO) film receives attention from the field of optoelectronics due to its wide band gap and high transparency. By using a sparking method, the deposition of the NiO film is facile and unique. However, the NiO film made by the sparking method indicates a porous surface with an agglomeration of its particles. In order to reduce the porousness of the NiO film, the assistance of a permanent magnet in the sparking apparatus is presented. Here, we report the investigation of the NiO film and the p-NiO/n-ZnO heterojunction deposited by the sparking method under a magnetic field. Our results demonstrate that the porosity of the NiO film was reduced by increasing the magnitude of a magnetic field from 0 mT to 375 mT. Furthermore, the crystallinity and the electrical properties of the NiO film are improved by the influent of a magnetic field. For heterojunction, the best device shows the rectification ratio of 95 and the ideality factor of 4.92. This work provides an alternative method for the deposition of the NiO film with promising applications in optoelectronic devices.

Vanadium dioxide (VO₂) is a typical thermal induced phase transition material, exhibiting a transition from metallic phase at high temperature to insulating phase at low temperature, which is also accompanied by a conductivity change of over several orders of magnitude. The transition property makes VO₂ prominent to achieve an effective degree of control of terahertz (THz) wave. In this paper, composite films consisting of metal grating with different periods and VO₂ film were prepared by polymer assisted deposition method. Although the conductivity change of VO₂ films deposited on gold grating structure across phase transition was declined to about two orders of magnitude, the amplitude modulation depth of THz of the composite films can still reach a high value. Furthermore, it was found that the THz modulation depth was related with the grating period. According to theoretical simulation, the fluctuation height of VO₂ films, caused by metal grating structure during growth, can be used to regulate THz wave. These results demonstrate an economic and unsophisticated method to fabricate VO₂ films with thickness fluctuation structure and then tune the THz waves.

A superhydrophobic surface featuring high roughness and low surface energy is designed for effective corrosion protection on aluminum via a facile and cost-effective electrochemical route. The effects of the electrolyte composition and electrodeposition time on the surface wettability were investigated. Moreover, the corrosion resistance performance of the as-prepared superhydrophobic aluminum surface was studied using electrochemical impedance spectroscopy and electrochemical noise techniques. The results show that the superhydrophobic aluminum surface obtained at 2 V for 20 min has a high static water contact angle of 155.8°. Both the average corrosion rate and pitting intensity are remarkably inhibited by the as-prepared superhydrophobic surface on aluminum. Moreover, the static water contact angle for the obtained superhydrophobic surface remains above 150° after exposure to 3.5 wt% NaCl solution for 30 days. This facile and economical superhydrophobic surface, with its excellent anti-corrosion property and stability, shows significant potential for use in industrial applications.

Six YSZ thin films (YSZTFs) were prepared at varied annealing temperature (380 °C to 600 °C) by radio frequency magnetron sputtering method. Glancing angle x-ray diffraction (GAXRD) pattern revealed the polycrystalline nature of all films with crystallite size in the range of 9 to 15 nm. Sample annealed at 400 °C displayed the lowest microstrain (0.262) and crystallinity (60%). FESEM images disclosed dense, homogeneous and crack free growth of annealed samples compared to as-deposited one. EDX spectra detected the right elemental compositions of films. AFM images showed growth evolution of YSZ grains with size range between 0.2 to 5 nm and improved films' surface roughness. HRTEM measurement of the studied YSZTFs exhibited lattice orientation and atomic structure of nucleated YSZ nanocrystallites. Furthermore, film annealed at 500 °C divulged less oriented structure because of dislocation.

The copper clad aluminum (CCA) wire was fabricated by roll forming of copper foil around the aluminum wire rode. Non-continuous wire drawing (NCWD) was employed to study the effect of wire drawing parameters on ductility, micro-hardness and microstructure of the copper clad layer. The NCWD process continued without intermediate annealing until cracks were observed on the copper clad layer. The cracks appeared after a 78% reduction in the cross-section. The micro-tensile test was performed on specimens with transverse curvature to determine elongation. A modified correction factor was introduced to correct the effect of curvature size on elongation. The introduced correction factor proportional to the sample characteristics was between 0.7 and 1.4. Moreover, variations in the hardness and microstructure of the copper clad layer were investigated in the base metal and at the welding zone. Before beginning the wire drawing process for the annealed CCA wire with a diameter of 10.1mm and a Cu clad thickness of 0.48mm , the hardness, ductility, UTS and grain size of the clad layer were 87HV, 43%, 103MPa and 80 μm, respectively. At the end of NCWD for 10° and the 20% reduction ratio of the die, the diameter of CCA wire reached 4.7mm with a 0.22mm thickness of Cu clad. The hardness, ductility, UTS and grain size of the clad layer were 157HV, 2.9%, 325MPa and 8 μm, respectively.

The effects of antimony (Sb) on the deformation behaviour of high-grade non-oriented silicon steel at a low temperature were studied by using a Gleeble-3800 thermal simulator and the field-emission scanning-electron microscope. The tensile strength of the high-grade non-oriented silicon steel without Sb was significantly lower than that of the high-grade non-oriented silicon steel with Sb within the tensile temperature range of 25 °C–240 °C. It is possible for Sb atoms near the grain boundary to diffuse at hundreds of atoms through dislocations as a rapid diffusion channel, which is driven by thermal activation with an increase in temperature. Atomic diffusion can weaken the damage to bonding forces on the grain boundary and crack propagation along the grain boundary under load action. The segregation of Sb atoms at the grain boundary decreased gradually, which weakened the cleavage characteristics of the fracture morphology and enhanced its dimple characteristics. For a stretching temperature of 80 °C, the fracture dimple of high-grade non-oriented silicon steel without Sb was significantly more than the high-grade non-oriented silicon steel with Sb. Because of the weakening effect of Sb segregation at the grain boundary, the suitable low-temperature deformation range for high-grade non-oriented silicon steel with Sb was 120 °C–160 °C.

A new two-step selective laser remelting (SLR) process was proposed to fabricate 316L stainless steel. The density, surface roughness, and mechanical properties were investigated by a multifunctional density tester, surface roughness meter, and tensile testing machine. Compared with the single-melting selective laser melting (SLM) process, the relative density, surface roughness (R_a), ultimate tensile strength, yield strength, elastic modulus, and elongation reached 99.31%, 6.67 μm, 725 MPa, 643 MPa, 13.95 GPa, and 40.8%, respectively. In addition, the microstructure and fracture characteristics were studied by OM, SEM, and EDS. The results showed little unmelted powder and fewer defects (balling, spatter, and cracks). In addition, a closer and smoother connection between the welds and equiaxed cell were obtained by the SLR process.

This paper presents a systematic study of the precipitation strengthening mechanism in polybasic Cu–Ni–Mn–Fe alloy. The effect of aging treatment on the microstructure, morphologies and phase transition of the Cu–Ni–Mn–Fe alloy were analyzed and discussed using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffraction (XRD) and differential scanning calorimeter (DSC), respectively. The θ-MnNi precipitates with a size of 50–100 nm, mainly formed during aging, were considered as the source of the aging strengthening. In addition, there is a semi-coherent between the plane (111) of the θ-MnNi precipitates and the plane (200) of the α-Cu matrix. The density of θ-MnNi precipitates increases with the increase of the aging time. The hardness, yield strength and ultimate tensile strength of the aged alloy increase from 127 to 366HB, 217 to 788 MPa, and 433 to 842 MPa, respectively, which is attributed to precipitation strengthening.

The mesoscopic dendrite growth model in the solidification process of molten steel is established, based on the cellular automata model. To accurately describe the TiN nucleation process, a heterogeneous nucleation model was used to describe the TiN nucleation process. The accuracy of the dendrite growth model is verified by comparing the CA model and Lipton–Glicksman–Kurz (LGK) analytical model. The growth process of TiN precipitates was simulated by dynamic mesh generation. Meanwhile, the influence of grid anisotropy on dendrite growth is greatly weakened by introducing the decentered square algorithm, and the growth of the equiaxed crystal in all directions is simulated. The results show that the calculated results of the model are in good agreement with the volume and morphology of TiN observed in the experiment. Meanwhile, it is found that the smaller TiN will dissolve at the end of solidification, and there will be a re-precipitation. The precipitation time of High-N and High-Ti alloy systems with the same concentration product is basically the same, but the final precipitation solid fraction of TiN inclusions in High-N (small Ti/N) alloy is larger. N element is the decisive factor of TiN precipitation.

The semi-solid billets of Mg-2.4Y-4Nd-0.5Zr-1Ni (WE34-1Ni) alloys are fabricated by electro-magnetic induction heating semi-solid treatment at 2.05 kW and 4.10 kW from 580 °C to 625 °C. In this work, the microstructure evolution and mechanical properties of WE34-1Ni alloys are investigated, and the results reveal that with increasing semi-solid temperatures, the average grain size of the solid globules and liquid fraction at the grain boundary gradually increase while the shape factor fluctuates slightly. Compared with 2.05 kW power, the semi-solid billet with 4.10 kW power at 625 °C has more fine homogeneous grains, the lower average size of the solid globules, more liquid fraction. The semi-solid billet with 4.10 kW at 625 °C obtains ideal semi-solid spheroid structure with the solid grains surrounded by a small amount of liquid pools and the best mechanical properties of the semi-solid process parameters. Besides, the elongation as-extruded of WE34-1Ni alloys increased from 21.4 ± 0.7% to 33.2 ± 0.3% at 4.10 kW power and 625 °C via electro-magnetic induction heating semi-solid treatment.

In this paper, the static recrystallization (SRX) of 12Cr ultra-super-critical (USC) rotor steel was investigated by a series of hot compression tests on a Gleeble1500D thermal simulator. Double-hit hot deformation tests were conducted at temperatures of 1223K–1323 K and strain rates of 0.001 s⁻¹–0.1 s⁻¹ with inter-pass times of 10s–180 s. A conventional kinetics model of SRX was established based on flow curves obtained by regression analysis under different deformation conditions. However, a significant deviation resulted between predicted and experimental values for the SRX fraction, and therefore a modified kinetics equation was proposed by analysing the SRX characteristics and possession of the capability to accurately predict SRX softening behaviour was confirmed. Effects of hot deformation parameters on SRX softening behaviour and SRX grain size were discussed. Furthermore, microstructure deforming was observed at different inter-pass times with an optical microscope (OM), electron backscatter diffraction (EBSD) and transmission electron microscope (TEM). Analysis showed that recovery was the main softening mechanism and the fundamental nucleation mechanism for SRX was bulging at the grain boundary.

Chromium carbides are coated over base metal (Fe) to increase wear and corrosion resistance. The electronic structure and bonding properties for chromium carbide bulk phases (Cr₃C₂, Cr₇C₃ and Cr₂₃C₆) and Fe-substituted chromium carbides is investigated using Density Functional Theory (DFT). The bonding in these carbides has been interpreted in the form of partial density of states, electron density distribution and Mulliken population method. Cr₃C₂ exhibits the strongest covalent character while Cr₇C₃ displays the highest metallicity. Cr₃C₂ showed the highest stability among the chromium carbide phases. In the Fe-substituted chromium carbides (Cr₂FeC₂), the site preference of Fe in Cr₃C₂ system has been reported. In Fe-substituted chromium carbides also show both of metallic and covalent character and Cr₂Fe3C₂ is found to be the most stable Fe-substituted chromium carbide system.

Powders could be based on solid particles or spongy particles depending on the powder manufacturing procedures. In this article, the numerical study of the cold compaction process for copper solid particles-based powder (i.e. Cu solid powder) and spongy particles-based powder (i.e. Cu sponge powder) has been carried out by using a two-dimensional multi-particle finite element method (2D-MPFEM) based on single action die compaction. The effects of internal pores content, external pressure, initial packing structure on the packing densification were systematically presented. Relative density, stress distribution, internal pore deformations, and force chain movements, particle rearrangement, and interfacial behavior within spongy particles were characterized and analyzed. The results reveal that the densification behavior of the sponge powder depends basically on the internal pore's content. Moreover, at low and medium relative density (ρ < 0.95), the densification behavior of the sponge powder is faster than solid particles-based powder. However, at higher relative density near unity, the force required to cause further compaction is significantly larger in the sponge powder. In addition, from the microscopic analysis, the deformation behavior of the particles and the internal pores and the force chain development rely mostly on the structure configuration, internal pore content and its position.

A1₃Zr/A356 Composite was prepared by in-situ reaction of K₂ZrF₆ powder and cast aluminum A356 melt at different temperatures (710 °C, 750 °C, 770 °C, 790 °C). The effect of different melting temperature on the morphology of Al₃Zr particles was studied, and the sliding friction and wear properties of the composites were studied by wear test. It can be seen from the x-ray diffractometer (XRD) that the prepared composite material consists of A1₃Zr and ɑ-Al, and also has a small part of the aluminum-silicon eutectic phase; SEM analysis shows that the particles of in-situ reinforced phase are fine, With the increase of temperature, the morphology of A1₃Zr reinforced phase changed from block to needle and strip, and the particle distribution of the reinforced phase was uniform and well dispersed in the matrix at 750 °C. TEM experiments show that the reinforced phase exists at 750 °C and has a good combination with the matrix, which plays a very good role in particle reinforcement Friction and wear experiments show that the different preparation temperature results in different phase morphology. The reinforced phase particles existing on the surface of composites at 710 °C and 750 °C bear most of the friction, so the friction coefficient of the composites is larger at these preparation temperature, and the main wear modes are oxidation wear and abrasive wear. The friction coefficient of the composites prepared at 770 °C and 790 °C is small, and the wear modes are mainly delamination wear and oxidation wear. When the preparation temperature is 750 °C, the wear resistance of the composites is the best.

Although many experimental researches have been carried out on the effect of different fluxes and the mechanism responsible for the higher penetration in activated TIG welding of magnesium alloy, few works as reported in literatures are available concering the grain refinement and the improvement of mechanical properties of welding joints. This is because the activated flux has very limited or even negative effects on improving the mechanical properties of welded joints. In order to find a method that can improve welding efficiency and mechanical properties of welded joints, the longitudinal alternating magnetic field and NiCl₂ activated flux were used during TIG welding of AZ91 magnesium alloy. The formation, mechanical properties, phase composition and crystal growth pattern of the weld seam were tested and analyzed to study the mechanism. The experimental results reveal that with proper parameter matching (magnetic field and activated flux), larger weld penetration and smaller form factor can be obtained, welding efficiency is improved accordingly, but the form factor with the magnetic field is bigger than that without magnetic field. When the activated flux amount is 3 mg cm⁻² with the magnetic field, the optimal value of mechanical properties of welded joint is obtained, tensile strength is 385 MPa, elongation is 13.3%, micohardness is 67 HV, respectively. All of these are better than those without the magnetic field, the optimal activated flux amount is 2 mg cm⁻². The application of magnetic field and activated flux has no noticeable effect on the phase composition of weld seam. Under the combined action of magnetic field and activated flux, the crystallization nucleation condition of molten pool was changed, the grain size was refined, the formation of twins was promoted, and the crystals selectively grew within the basal (0001) plane.

Thermal deformation of Mg-7.5Gd-2.5Y-1.5Zn-0.5Zr (wt%) as-cast alloy containing LPSO phase was been studied in a temperature range from 623 K to 723 K and a strain rate range from 0.001 to 1 s⁻¹. The microstructural evolution at the various strain rates was also analyzed. The results show that the flow stress decreases significantly with the increase of the deformation temperature. But the peak flow stresses of the alloy increase significantly at high deformation temperature, due to existing both the plentiful lamellar LPSO phase and the fine dynamic DRXed grains. Under the high strain rate conditions, the LPSO phase distorted and formed kink bands. The deformational activation energy (Q) of the alloy is about 234.6 kJ·mol⁻¹. This high Q value mainly owe to profuse lamellar LPSO phase hindering the movement of atoms. With the observation of established processing map of the alloy, some good thermal workabilities are observed in following zones: 723 K, 0.001 < ε < 1 s⁻¹; and the zone with middle temperature and moderate strain rate condition, 673 K, 0.01 < ε < 0.1 s⁻¹. The thermal deformation instability zones are mainly located in the region with high strain rate and lower temperature.

Some functional and structural performance of tungsten (W) are related to its texture characteristics. Usually, W serves in high temperature and may undergo recrystallization. Thus it's necessary to evaluate the recrystallization texture of W. In our previous studies, pure W (PW) and W-1.0wt%La₂O₃ (WL10) were deformed via unidirectional rolling (UNR), cross rolling (CRR) and clock rolling (CLR) with 80% reduction. In the present paper, PW-UNR, PW-CRR, PW-CLR and WL10-UNR were subjected to annealing at 2073 K for 2 h to achieve recrystallization and figure out the evolution mechanism of recrystallization texture in W materials. Besides, the effect of La₂O₃ on recrystallization texture of W was discussed. The results indicated that the fiber textures in rolling state were transformed into isolated textures after recrystallization. {001}〈uvw〉 isolated texture formed in the recrystallized W may be mainly resulted from the texture inheritance. {113}〈361〉 isolated texture formed in the recrystallized WL10-UNR may be attributed to the orientated growth of {113}〈361〉 grains with high grain boundary mobility facilitated by La₂O₃. Generally, isolated textures near θ-fiber were strengthened while γ-fiber was weakened for W during recrystallization, which is an effective method to achieve W with more {001} and less {111} textures.

A self-made line laser liquid level measurement system was used to measure the fluctuation of molten metal free surface under pulsed magnetic field. The electromagnetic characteristics of pulsed electromagnetic force were mathematically analyzed. Results showed that the electromagnetic force presents oscillatory attenuation during a single pulse period. The electromagnetic force was composed of turning force ${f}_{turn}$ and non-turning force ${f}_{nonturn}.$ The direction of ${f}_{turn}$ was always consistent with the melt circumferential direction, which turned the ${f}_{nonturn}$ consisted of electromagnetic pull and push forces, which caused the melt to oscillate. Under the pulsed magnetic field, the free surface formed a meniscus with a high middle, low side structure. With increased pulsed field intensity, the center surface of molten melt had an oscillation of ±3.52 mm at 0.187 T. The wave power density had only two spectral peaks (at 0.60 and 3.36 Hz) without a magnetic field. Under pulsed magnetic field, four spectral peaks were found at 0.40, 3.00, 6.50 and 13.00 Hz.

Localized electrochemical deposition (LECD) is a promising method for three-dimensional micro-/nanofabrication and, thus, the factors influencing LECD have been intensively investigated. This study examined the effect of sulfuric acid concentration on copper microcolumns deposited by LECD using a microanode with a diameter of 20 μm. With 0.05 mol l⁻¹ sulfuric acid, the deposition voltage of the optimal deposited morphology of copper microcolumns was at 2.9 V, but the column diameter was larger than the anode diameter. With 0.5 and 2.0 mol l⁻¹ sulfuric acid, the optimal deposited morphology of copper microcolumns were at 3.2 V and 3.4 V, respectively, but the diameters of the copper microcolumns were smaller than the anode diameter. In the LECD process, the deposition rate is proportional to the deposition voltage. Because of the hydrogen evolution, the deposition rates of copper microcolumns at high sulfuric acid concentration were lower than those at low and medium sulfuric acid concentrations. The results of this study indicated that the deposition rate obtained the optimal surface topography was 0.22 to 0.327 um s⁻¹, which had reference significance to improve the quality of the copper microcolumns. The effect of sulfuric acid on the LECD was demonstrated using a competitive reduction mechanism.

We have performed ab-initio electronic structure calculations to investigate the ground state properties of Pd_1−xNi_xTe (x = 0.0–0.20) alloys. The PdTe and all of its alloys are paramagnetic metals. For low concentrations, the band structure remains almost unchanged and at higher concentrations, a strong redistribution of spectral weights is observed. The most striking feature of the band structure is that the bands around the Fermi energy remain almost unchanged. The calculated Fermi surfaces are remarkably robust against disorder, strongly three-dimensional and have no or negligible nesting. The density of states at Fermi energy increases monotonically with concentration (x). Although the contribution of Ni to the density of states at Fermi energy is increasing continuously yet, Pd and Te dominate the density of states at Fermi energy. The density of states at Fermi energy and superconducting transition temperature T_c show opposite trends with respect to Ni concentration. So, density of states at Fermi level alone is not sufficient to discern the trends in T_c. We need to know the phonons and electron-phonon interactions as well, which at the moment are not available.

The effects of trace amounts of Sc/Zr on rheological properties and microstructural evolution of the Al-6Mg-0.4Mn-0.15Sc-0.1Zr alloy under different deformation conditions were studied by isothermal compression tests at deformation temperatures of 280 °C ∼ 460 °C and strain rates of 0.001 ∼ 10 s⁻¹. A constitutive model based on the hyperbolic sine function was established. The dependence of the flow stress on strain, strain rate, and deformation temperature was described. Using experimental data and dynamic material model, machining diagrams of the alloy with strains of 0.3 and 0.5 were obtained, and the hot workability of the alloy was verified. The results showed that the deformation temperature and strain rate had significant effects on the deformation behavior of the alloy. The flow stress of the alloy increased with the increase in strain rate and decreased with the increase in deformation temperature. Under high-temperature and low-strain-rate conditions, the alloy tended to undergo dynamic recrystallization, and the volume fraction and grain size increased with the increase in deformation temperature and the decrease in strain rate. Based on the analysis of the microstructural evolution, the construction of the machining diagram, and the solution of the rheological constitutive equation, suitable values of the deformation temperature were determined to be 380 °C ~ 460 °C. Moreover, suitable values of the strain rate were determined to be 0.001 and 0.3 s⁻¹. The deformation activation energy of 161.28 kJ mol⁻¹ was obtained.

Simulations of the welding process for butt joints using finite element analysis (FEA) of the effect of porosity are presented. The metal used was aluminium alloy (grade 2024), and the filler material was alloy ER5356. The simulations were performed using the commercial software ANSYS, considering a double ellipsoid heat source, temperature-dependent material properties, material deposits, mechanical analysis, transient heat transfer, and defects (porosity). In this study, the FEA simulations were constructed for two types of heat source (single- and double-ellipsoid) used in gas tungsten arc welding (GTAW), and the calculated residual stress results were compared with the experimental values. Two double ellipsoid models were constructed for cases with and without porosity. The porosity was measured by three-dimensional (3D) computed tomography (CT), and the size and location of pores were mapped onto the weld bead created by the birth-and-death technique.

TiAlSiN coating was painted on the surface of 42CrMo steel by arc ion plating technology, and the influence of excitation coil voltage on the structure and friction property of the coating were analyzed. Results showed that there were a lot of holes on TiAlSiN coatings under different voltages. With the increase of voltage, the structure and friction property changed a lot: the roughness and thickness of the coating increased obviously and all layers were in a state of tight bond and formed a columnar structure; many voids appeared led to the decrease of coating density; the coating with higher microhardness was obtained, which was higher than that of alloy steel substrate; the friction coefficient and wear rate of the coating first decreased then increased, and the minimum wear rate occurred when the voltage reached 30 V, under condition of which the coating mainly suffered from abrasive wear, so more flat surface and denser structure of the coating formed, which significantly improved the wear resistance.

The microstructure and erosion-corrosion performance of Fe–Cr–Ni–B alloy were studied. The experimental results were analyzed by hardness tester, energy spectrum analyzer, scanning electron microscope, X-ray diffraction analyzer. The results show that the Fe–Cr–Ni–B alloy consists of martensite and borocarbides [M₂(B, C) and M₇(B, C)₃], and M₂(B,C) and M₇(B,C)₃ borocarbides both have more chromium and less nickel than the matrix. After heat treatment, the hardness of the alloy reaches 52.3HRC. For the test alloys, the higher rotating speed test condition results in higher erosion-corrosion weight loss, and the erosion-corrosion weight loss increases first and then decreases with the increase of the impingement angle. Compared with Cr28 high chromium cast iron, in the erosion-corrosion surface of Fe–Cr–Ni–B alloy, the borocarbides are slightly broken, so, the Fe–Cr–Ni–B alloy exhibits excellent erosion-corrosion resistance under the borocarbide protection.

In this study, the dynamic impact tests of spray-deposited 17 vol% SiCp/7055Al composites at various strain rates were performed with a Split Hopkinson Pressure Bar (SHPB). In these tests, the strain rate was 392 s⁻¹–2002 s⁻¹, and the temperature was 293 K–623 K. Subsequently, the Johnson-Cook (JC) was used to describe the flow behaviors under high speed impact deformation, and its effectiveness was assessed. Results show that the stress values predicted by the JC model could be inconsistent with the experimental ones. A modified JC constitutive model of 17 vol% SiCp/7055Al composites was developed by modifying the strain rate hardening term and considering coupling effects of strain, temperature and strain rate. According to the comparison between the experimental data and the results assessed with the modified JC model, the proposed model could assess the stress-strain values more accurately, especially in the beginning of plastic deformation. This indicates that the composites exert the joint effects of strain rate hardening and temperature softening during high-speed impact deformation.

The effect of different (T6 and T8) heat treatments on tensile properties and fracture behavior of Al2024 in presence and absence of notch by means of microhardness, tensile tests and scanning electron microscopy were investigated. Tensile and hardness specimens were subjected to two different artificial ageing (T6 and T8 heat treatment) for various times. These included under ageing (UA), peak ageing (PA) and over ageing (OA). T8 heat treatment, which has a cold rolling between solutionizing and ageing in its steps, showed a higher value of hardness and yield strength in comparison with common artificial ageing of T6 heat treatment. In notched-tensile specimens, yield stress was found to increase up to the peak ageing condition with a simultaneously decrease in elongation at fracture. This behavior was converse at OA condition. Although introducing of notch increase the yield stress of samples under T6 and T8 conditions in comparison with un-notched samples, the notch strengthening phenomenon was observed only under T8 treatment. Despite of an enhancement in strengthening by applying notch on tensile samples, the elongation to failure was notably lessen in both notched-heat treated samples in comparison with un-notches ones. Also, it was confirmed that the toughness of notched samples of both heat treatments at PA condition were significantly lower than un-notched ones. Consequently, toughness decrement was considerably dominated by the role of deformability compared to strengthening factor, however, the presence of cold rolling in the process of heat treatment (T8) could reduce the harmful effects of notch by increasing the stress bearing capacity in contrary with T6 heat treatment. Moreover, inserting the mechanical properties of peak aged samples from the un-notched tensile test in Abaqus finite element software; the V-shaped notch tensile test was simulated and confirmed the experimental results. It was shown in SEM results that the presence of notch enhanced the contribution of cracked particles, compared to particle/matrix deboning and matrix deformation, therefore, the non-homogeneous distribution of fracture features confirmed the harmful effect of notch. In the following, the distribution of three fracture micro-mechanisms were homogeneous in un-notched samples, which demonstrated the superior values of toughness in smooth samples. The present finding sheds light on development of processing techniques to optimize the mechanical properties of Al 2024 alloy.

This study was focused on structural, electronic and vibrational properties of Li₂CaSn and Li₂CaPb with density functional theory. All properties of these compounds were computed by implementing General Gradient Approximation and using Quantum Espresso software programme. As a result of the calculations, it was found that the lattice parameter is 6.967 Å and bulk modulus is 33.94 GPa for Li₂CaSn. Also, these values are 7.062 Å and 29.574 GPa for Li₂CaPb. The calculated lattice parameters are in good agreement with the available experimental data. There is no previous theoretical calculation for Li₂CaSn and Li₂CaPb compounds. It was calculated that Li₂CaSn and Li₂CaPb have a semi-metal property. The full phonon dispersion curves of Li₂CaSn and Li₂CaPb compounds in the Heusler type structure were examined using the linear response method. Under 0 kbar pressure, Li₂CaPb was unstable while Li₂CaSn was dynamically stable. Calculations showed that when 38.42 kbar pressure is applied to the Li₂CaPb compound, the Li₂CaPb compound becomes dynamically stable. It is believed that this study will shape future studies.

In this work, the effects of C, N, and Al on the microstructures and creep properties of Fe–Cr–Al–Nb–W ferritic alloys were investigated through scanning electron microscopy, x-ray diffractometry, as well as uniaxial creep testing and hardness testing. The results demonstrated that the matrix of the Fe–Cr–Al–Nb–W heat-resistant steel was ferrite, while the precipitation phases were Laves phases, M₂₃C₆ carbides and MX nitride phases. M₂₃C₆ and MX precipitated at grain interior, Laves phases precipitated at grain interior, grain boundary and around MX phases. C, N and Al affected microstructure and creep of heat-resistant steel. As the Al content increased or as N content decreased along with the C increase, the average diameter of the Laves phases, along with M₂₃C₆ and MX phase grain interior decrease. Moreover, the unit density increased and the phase spacing decreased, which led to the minimum creep rate decrease and creep rupture time increase. Compared to M₂₃C₆, Laves and MX phases mainly affected the alloy creep strength. The decrease of Laves phase continuity coefficient (ratio of Laves phase particle spacing and size) on the grain boundary was conducive to the plasticity improvement of heat-resistant steel.

To reveal the formation and wear mechanisms of rheo-formed aluminum alloy - B₄C composites, A356 alloy − 10 mass% B₄C composite material was fabricated by semi-solid stirring rheo-casting and rolling process. The presence of Al₃BC was confirmed by XRD analysis and hinted that chemical bonding formed at interfaces between aluminum matrix and B₄C particles. Tensile test results demonstrated that addition of B₄C facilitated improving the tensile strength by refining matrix and providing particle strengthening. Failure tests revealed that the failure type of the composite transferred from interfacial debonding to particle cracking with increasing wear load. The wear rate of the composite was approximately 48% lower than that of aluminum alloy under 60 N load. The friction coefficient of the composite under 60 N load also significantly decreased due to formation of B₂O₃ and H₃BO₃ as solid lubricants.

Magnesium-based composites with carbonate apatite reinforcement are attractive biodegradable implant materials. In this study, we observed the effect of carbonate apatite content (5, 10, and 15% wt.) and milling time (3, 5, and 7 h) on the microstructure and microhardness of magnesium-carbonate apatite composites fabricated by powder metallurgy. The consolidation process involved warm compaction without sintering. Characterization was achieved through density testing, x-ray diffraction (XRD), optical microscopy, SEM-energy dispersive x-ray spectroscopy (EDS), and microhardness testing. The powder milling time affects the distribution of apatite carbonate; adding carbonate apatite can increase the hardness of magnesium-based composites. In the XRD spectrum, we identify the dominant magnesium peak but not the magnesium oxide peak. Carbonate apatite powder is distributed at the grain boundaries. The hardness range is 40.26–44.82 Hv or increase by 8.21%–20.23% compared to the hardness of consolidated pure magnesium. The relative density is around 95.92%–98.71%, whereas the relative density of pure magnesium is 99.58%. The obtained optimal conditions for fabricating magnesium composites are the following: content of 10 wt% carbonate apatite (milled for 5 h) with a hardness of 43.58 Hv.

Nickel-based superalloys are widely used at elevated temperature applications because of their high corrosion and oxidation resistance characteristics as well as high stability. To improve the hot corrosion resistance of Nickel-based superalloys, different coatings are applied. In this study, nickel-base superalloy Inconel 738LC was coated via a novel hot-dip diffusion siliconizing process and the corrosion behavior was investigated by XRD, SEM and EDS analyses. A sever degradation and poor hot corrosion resistance was detected by the uncoated sample, while the siliconized coated sample possessed high corrosion resistance. It was figured out that the high hot corrosion resistance of the coated sample was due to the formation of SiO₂ protective scale in the surface layer which protects the substrate elements in the hot corrosion environment.