Formation Of Phase Structure Research Articles

MFe2O4 (M: Cu, Ni)/SnS2magnetic Core-Shell Heterostructure for Photocatalytic H2 Generation and Environmental Remediation

Overgrowing demand for sustainable energy sources and environmental remediation has driven extensive research in the field of photocatalysis. This study presents a hydrothermal synthesis of a novel MFe2O4 (M: Cu, Ni)/SnS2 magnetic core-shell heterostructure. The engineered heterostructure combines the unique properties of MFe2O4 (M: Cu, Ni) magnetic crystal as a core with SnS2 nanosheets as a shell, aiming to exploit type-2 heterojunction properties to improve effects for improved photocatalytic performance. The structural chemistry, phase formation, and crystal orientation of the prepared material are investigated using various analytical techniques, including X-ray diffraction (XRD), transmission electron microscopy (TEM), Raman, and FTIR Spectroscopy. FE-SEM analysis reveals a well-defined core-shell morphology with intimate interfaces between MFe2O4 (M: Cu, Ni) crystals and SnS2 nanosheets. Photocatalytic efficiency is assessed through the industrial dye degradation process. The influence of the heterostructure's structural features on the photocatalytic activity is explored through density function theory, emphasizing the role of the core-shell interface and the magnetic properties of MFe2O4 (M: Cu, Ni) cores. The chemistry between the magnetic core and the shell in the heterostructure is demonstrated to be crucial for optimizing charge carrier dynamics and promoting surface reactions. Photocatalytic H2 generation under artificial simulated sunlight irradiation in the presence of MFe2O4 (M: Cu, Ni)/SnS2 core-shell heterostructure is demonstrated. This study not only presents a novel MFe2O4 (M: Cu, Ni)/SnS2 heterostructure for photocatalytic H2 generation but also provides valuable insights into the intricate relationship between structural chemistry and photocatalytic efficiency. The engineered heterostructure shows promising potential for applications in sustainable energy production and environmental remediation, contributing to the ongoing efforts towards a cleaner and more sustainable future.

Investigation of structural, morphological, and ionic conduction behaviour of Na+ substituted trimeric strontium silicate Sr3–3xNa3xSi3O9-δ (0.00 ≤ x ≤ 0.20)

Extensive research has been carried out to search new electrolytes for Solid Oxide Fuel Cells (SOFCs) in order to reduce their operating temperature in the intermediate temperature range (500 ̊C < t < 800 ̊C) for wide commercialization. Recently, alkali doped strontium silicates materials have been reported to show adequate ionic conductivity in the intermediate temperature range. Hence, in the present work, we have tried to synthesize trimeric Sr3–3xNa3xSi3O9-δ (0.00 ≤ x ≤ 0.20; SNS) system and did a comprehensive study on this system to examine its applicability as a solid electrolyte for electrochemical devices such as IT-SOFCs. The SNS system was prepared via solid state reaction route and characterized by means of XRD, FT-IR and Raman spectroscopy to authenticate the structural phase formation and to gather its spectroscopic traits. The optical Energy band gap of the system was calculated by means of UV-Visible absorption spectroscopy. Surface morphology, microstructure and elemental confinement of the system was examined via Scanning Electron Microscopy (SEM) and Energy dispersive spectroscopy (EDX) techniques. The ionic transport study of the system has been conducted via AC conductivity analysis and Electrical Impedance Spectroscopy (EIS) technique. The highest total conductivity ∼ 0.46×10−2 Scm−1 at 650 ºC was found for the composition Sr2.40Na0.60Si3O9-δ thru EIS method.

Hydrothermally grown pure and Er-doped ZnS nanocrystals based flexible piezoelectric nanogenerator for energy harvesting and sensing applications

Pure zinc sulphide (ZnS) and Er-doped ZnS nanocrystals were grown by hydrothermal method at low temperature. Powder XRD analysis reveals the formation of wurtzite hexagonal phase structure for both pure and Er-doped ZnS samples. Morphology of 2D nanocrystals for both pure and doped ZnS nanocrystals was confirmed by FESEM technique. Presence of Er element in Er-doped ZnS was confirmed by energy-dispersive X-ray spectroscopy. Further, both pure and Er-doped nanocrystals have been used as piezoelectric fillers in polydimethylsiloxane (PDMS) for the fabrication of flexible piezoelectric nanogenerators. The Er-doped ZnS based nanogenerator showed almost 9 times (∼ 36 V) higher open circuit voltage as compared to pure ZnS based nanogenerator (∼ 4 V). Then, Er-doped ZnS nanocrystals based device was used to harvest the mechanical energy under the human walking and running conditions. Also, this device generated significant electrical signal under the human elbow bending. The output performances of Er-doped ZnS based device indicates that it can be a potential candidate for mechanical energy harvesting under various human body motions as well as for wearable piezoelectric sensor applications.

Synthesis and luminescence properties of a bluish-green -emitting Sr3LiSbO6: Pr3+ phosphor for optoelectronic applications

The present work explores the significance of charge transfer band (CTB) excitation, with large absorption capacity, of Pr3+ doped Sr3LiSbO6 phosphor materials for bluish-green emission. Phosphor materials were synthesized via the conventional high-temperature solid-state method. The formation of phase structure was confirmed by XRD. The structural parameter was estimated from Rietveld refinement. Field emission scanning electron microscopy (FESEM) and High-resolution transmission electron microscopy (HRTEM) coupled with mapping and EDX spectroscopy were employed to get high-resolution images of morphologic structure. Raman and FTIR spectra were investigated to detect the presence of different vibrational levels and functional groups respectively. The elemental compositions were further confirmed via XPS survey scan spectrum and their oxidation state was also explored. The optical band-gap was found to increase first with doping concentration and then start to decrease after doping of 2 mol%, this result was further supported by photoluminescence (PL) emission spectra. PL emission spectra presented the characteristic peaks of Pr3+ due to f-f transitions. PL emission spectra illustrated that the concentration quenching took place at 2 mol% doping of Pr3+, which was governed by dipole-dipole coupling. The decay curves of each sample were recorded for specific excitation and emission wavelengths of 262 nm and 490 nm respectively. All the decay curves were well-fitted with single exponential function. The observed average decay time was 10.5 μs. Afterward, photometric studies including Chromaticity International d’Eclairage (CIE), correlated color temperature (CCT) and color purity (CP) were performed. Calculated CIE values were found to lie in bluish-green regions with lower CP and higher CCT. These results obtained from various characterizations conclude that the proposed Sr3LiSbO6 phosphor, doped with various concentrations of Pr3+ (0 mol% to 7 mol% of Pr3+), reveal their applicability in the field of solid-state lighting for white light emitting diodes.

Effect of blend ratio on the phase structure and ozone aging resistance of ethylene-propylene-diene, butyl, and chlorobutyl rubber blends

ABSTRACT In the present study, the effect of elastomer ratios in solution-based mixtures on the formation of the phase structure and properties of compositions based on butyl rubber, chlorobutyl rubber, and ethylene-propylene-diene rubber was investigated. This work determined the influence of the elastomer ratios in uncured blends and their impact on the patterns of phase structure formation in multicomponent polymer systems, alterations in molecular mobility, and their influence on ozone resistance. Attenuated total reflectance – Fourier transform infrared spectroscopy was employed to analyze the chemical structure of the polymer surfaces. The influence of blend ratio (mass percentage ratios of 100/0, 80/20, 60/40, 50/50, 40/60, 20/80, and 0/100) on the phase structure and surface ozone oxidation was studied. The green strengths of the blends of ethylene-propylene-diene rubber and butyl/chlorobutyl rubbers were studied over a wide range of blend ratios.

Radiation Synthesis of High-Temperature Wide-Bandgap Ceramics.

This paper presents the results of ceramic synthesis in the field of a powerful flux of high-energy electrons on powder mixtures. The synthesis is carried out via the direct exposure of the radiation flux to a mixture with high speed (up to 10 g/s) and efficiency without the use of any methods or means for stimulation. These synthesis qualities provide the opportunity to optimize compositions and conditions in a short time while maintaining the purity of the ceramics. The possibility of synthesizing ceramics from powders of metal oxides and fluorides (MgF2, BaF2, WO3, Ga2O3, Al2O3, Y2O3, ZrO2, MgO) and complex compounds from their stoichiometric mixtures (Y3Al3O12, Y3AlxGa(5-x) O12, MgAl2O4, ZnAl2O4, MgWO4, ZnWO4, BaxMg(2-x) F4), including activators, is demonstrated. The ceramics synthesized in the field of high-energy electron flux have a structure and luminescence properties similar to those obtained by other methods, such as thermal methods. The results of studying the processes of energy transfer of the electron beam mixture, quantitative assessments of the distribution of absorbed energy, and the dissipation of this energy are presented. The optimal conditions for beam treatment of the mixture during synthesis are determined. It is shown that the efficiency of radiation synthesis of ceramics depends on the particle dispersion of the initial powders. Powders with particle sizes of 1-10 µm, uniform for the synthesis of ceramics of complex compositions, are optimal. A hypothesis is put forward that ionization processes, resulting in the radiolysis of particles and the exchange of elements in the ion-electron plasma, dominate in the formation of new structural phases during radiation synthesis.

Phase behaviour and structure formation of alginate-gelatin composite gels

Alginate-gelatin composite gels are widely used in food and biomedical applications. These composite gels are particularly interesting for their ability to establish complex functionalities, such as in bioinks for 3D bioprinting. In order to understand and optimise their techno-functionalities, it is crucial to study the structure formation, which is influenced by molecular interactions and phase behaviour.Therefore, the aim of this study was to characterise the effect of mixing ratio and temperature (21 and 40 °C) on the phase behaviour and structure formation of alginate-gelatin composite gels using internal alginate gelation with Ca-EDTA and D-glucono-δ-lactone. We compared pure alginate gels and composite gels using oscillatory rheology, pH measurements during gelation and microstructural analysis through confocal laser scanning microscopy.The temperature-dependent state of the gelatin - liquid or gelled - strongly influenced the gelation velocity of alginate. At 40 °C, liquid gelatin delayed the gelation process by buffering the pH decrease. This effect was most pronounced in the presence of excess gelatin, which had a strong antagonistic effect on gel strength. At 21 °C, gelled gelatin resulted in a faster alginate gelation and the formation of phase-separated networks at all mixing ratios. This was also accompanied by antagonistic effects on the gel strength. The phase-separated networks showed different microstructures with high-contrast regions depending on the mixing ratio, which correlated with variations in the turbidity of the gels. These insights into the structure-function relationship of alginate-gelatin composite gels may enable the customisation of specific network types for the use in 3D bioprinting.

The gradient high entropy alloy coating prepared in-situ by bidirectional diffusion of Mo/Nb and FeCoCrNi

Based on the influence of Mo and Nb content on the eutectic degree of FeCoCrNi high-entropy alloy (HEA), this study prepared in-situ HEA composite coatings with a gradient eutectic degree using the principle of element diffusion in the molten pool under a laser beam, namely Mo-CC and Nb-CC. Both of the two coatings were composed of the face-centered cubic (FCC) phase and Laves phase. Within the coating, there was a gradual decrease in the Laves phase and an increase in the FCC phase from top to bottom. The Laves phase in Mo-CC was rich in Mo (21.36 at.%) element and exhibited an orientation relationship with the FCC phase of [01¯1]Laves//[01¯1]FCC. The phase interface was a non-coherent crystal plane. The Laves phase in Nb-CC is enriched with Nb (36.15 at.%) element and demonstrated an orientation relationship with the FCC phase of [1¯2¯1]Laves//[001]FCC. The phase interface was a semi-coherent crystal plane. Furthermore, the process and mechanism of FCC phase transformation into FCC + Laves phase were elucidated by examining the mixing enthalpy, lattice distortion, and atomic radius difference. In terms of properties, the hardness of Mo-CC and Nb-CC from the top to the bottom section gradually decreased from the outer to inner section. Nb-CC possessed a higher surface average hardness (773.66 HV0.3) and superior tribological properties compared to Mo-CC. The gradient control method for HEA and the phase structure formation mechanism presented in this study provided valuable insights for the research and development of new HEA coatings.

Unveiling the transformation pathways of hierarchical γ90 – εtwin – α’ triple phase structure formation at ε-ε martensite intersection

Deformation-induced martensitic transformation (γ-austenite → ε-martensite/α’-martensite) in austenitic steels has garnered significant interest owing to its transformation-induced plasticity effect. To elucidate the orientation-dependent intricate γ/ε/α’ phase microstructure at deformation-induced ε-ε intersection, a single crystal of 316 austenitic stainless steel was compressed along the [001]γ axis at a cryogenic temperature (173 K). Electron backscattered diffraction analysis was employed to reveal the deformed microstructure on the (110)γ surface. A hierarchical triple phase structure was discovered at ε–ε intersection, where the γ rotated 90° from the matrix (γ90), {101¯2} ε-twin, and α’ phases coexist. Depending on the operative shear angle with a common intersection axis, either 90° (Type I) or 30° (Type II), three distinct atomic rearrangements of the intersection volume were observed: γ90 was present at Type I intersection, and α’-phase was developed at Type II intersection, respectively. {101¯2} ε-twin also occurred at Type I intersection, serving as an accommodation mechanism alongside the intersection γ90. EBSD results confirm the Shoji–Nishiyama (SN), Kurdjumov–Sachs (KS), and Burgers (B) orientation relationships within the complex γ – ε – α’ triple phase structures at ε–ε intersection. Transformation paths for three intersection products were visualized by the unified tetrahedron model, considering T/2 or T/3 γ-twinning shear as an intermediate state. Moreover, a novel scheme is proposed to index the α’-martensite crystallographic variants at ε-ε intersections by establishing a correlation between the Bain distortion and double shear process.

Enhancing structural properties of simple perovskite materials based on zirconate and titanate prepared by sol-gel method

A simple and effective method is used in this study in order to obtain lead and lead-free simple perovskite structures. The perovskite materials BaTiO3, BaZrO3, PbTiO3 and PbZrO3 were synthesized via the sol-gel method. The main aim of this study is to investigate the effects of calcination temperature and rate on the material's properties. The structural phase formation of the prepared materials was characterized using X-ray diffraction (XRD), Raman spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The results gathered show that perovskite compounds based on barium occur at higher crystallization temperature, 900 and 1000 °C for BaTiO3 and BaZrO3 respectively, than the ones based on lead, 680 °C for PbTiO3 and PbZrO3. On the other hand, zirconate materials begin to crystallize at relatively high temperatures (1000 °C for BaZrO3 and 680 °C PbZrO3), than titanate-based materials (900 °C for BaTiO3 and 600 °C for PbTiO3). Also, the results showed, the obtaining of the non-centrosymmetric perovskite structure, indicating that piezoelectric property is present for all the elaborated materials.

Hybridization Effect of Nickel-Zinc Coating on Carbon Steel for Service Life Improvement

Deterioration of metals and alloys due to corrosion has been observed to be a serious challenge in coastal or marine environments. Exposure of mild steel to marine environments often results into dilapidation of physical structure over time. This study addresses the quick response of mild steel failure using NiZnP modified Al2O3 functional composite by electrolytic process. The deposition was done with stable pH of 4.5, heated bath temperature of 95°C, stirring rate of 200 rpm and deposition time of 20 min. The materials chemistry of the developed alloy was examined using open circuit potential and linear polarization technique. The structural mechanism and crystal phase formation was characterized using scanning electron microscope (SEM) equipped with energy dispersive spectrometer (EDS) and X-ray diffraction analyzer. The corrosion results under 3.65% saline environment reveals improved corrosion rate of NiZnP modified Al2O3. The surface site of the crystal formation evolves perfectly with hexagonal structure seen along the grain boundaries.

Novel Green Synthesis of UV-Sunscreen ZnO Nanoparticles Using Solanum Lycopersicum Fruit Extract and Evaluation of Their Antibacterial and Anticancer Activity

This work aimed at the green synthesis of multifunctional zinc oxide nanoparticles (ZnO NPs) using Solanum Lycopersicum (SL) fruit juice to act as antibacterial/cancer/UV sunscreens. The obtained ZnO NPs were examined for optical properties, cytotoxicity of human lung fibroblast (WI-38) and hepatocellular carcinoma (HePG2) cell lines, and antibacterial activity against Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus. The antioxidant activity and in vitro sun protection factor (SPF) of the synthesized nanoparticles were carried out by spectrophotometric methods. The formation of pure phase structure and characteristic functional group of the synthesized ZnO NPs were confirmed by XRD, FTIR, and UV–Vis diffuse reflectance analysis. SEM image showed that the ZnO NPs have a quasi-spherical shape with a size of about 39 ± 12 nm. ZnO NPs showed high potency as sunscreens (in vitro SPF = 16.8) and as mild antioxidant agents. Notably, ZnO NPs enhanced the cytotoxic activity against hepatocellular carcinoma cells and confirmed their antibacterial activity against pathogenic bacteria. SL fruit juice can play a triple role by acting as a solvent, reducing agent and stabilizer which facilitates the synthesis of ZnO NPs sunscreen that has antibacterial and anti-carcinogenic properties.

Modulating of Bouligand Structure and Chirality Constructed Bionically Based on the Self-Assembly of Chitin Whiskers.

Chitin can self-assemble into a liquid crystal phase with supramolecular chirality and Bouligand structure, which is widely found in the exoskeletons of arthropods. However, bionically replicating this structure via the self-assembly of chitin whiskers (CHWs) is still a challenge. Here, the effects of several internal and external parameters on the self-assembly of CHWs were revealed based on liquid crystal phase, chirality, Bouligand structure, and rheological properties. The formation of chiral liquid crystal phase and Bouligand structure largely depends on the concentration of CHWs and, meanwhile, is affected by the aspect ratio and zeta potential of CHWs and the self-assembly time. Impressively, introducing electrolytes and changing pH significantly affect the thickness of the electrical double layer, thereby also affecting the self-assembly of CHWs. This study offers a comprehensive understanding of CHWs' self-assembly process, which is beneficial for the bionic design of new nature-inspired functional materials with chiral characteristic and Bouligand structure.

Induced nonstoichiometric effects of Sb in p-type skutterudite thermoelectrics

Sublimation of antimony (Sb) during synthetic processes can be fatal to the thermoelectric (TE) properties of MT4Sb12 (M: filler atoms; T = Fe, Co, Ni)-based skutterudite (SKD). In this study, the nonstoichiometric effects of Sb on the phase structure formation and, thereby, on the TE properties of p-type SKD with Nd0.9Fe3.5Co0.5Sb12+x compounds were systematically investigated. Research is carried out with x values varying from −0.8 to 1.0, and samples are prepared by combining induction melting and melt-spinning, followed by a spark plasma sintering (SPS) process. The analysis showed that the Sb-deficiency formed NdSb and FeSb2 secondary phases along with the SKD main phase, while the Sb-excess effectively suppressed the FeSb2 phase formation and a small amount of the Sb phase appeared at a high Sb-excess level. The appearance of the secondary phases induced by Sb nonstoichiometry directly affected the change in the filling fraction of Nd in the SKD crystal structure, which led to the carrier concentration change. Our results demonstrate that the TE performance of MT4Sb12-based compounds can be significantly changed by the Sb nonstoichiometry, which should be profoundly considered along with other strategies to improve the TE efficiency of Sb-based SKD materials.

Effect of annealing temperature and thickness on the structural and optical properties of strontium bismuth niobate films

Strontium Bismuth Niobate (SBN) thin films were prepared by metal organic decomposition method. The effects of post deposition annealing temperature (500–900 °C) and thickness (200–650 nm) on the structural and optical properties have been discussed. X-ray diffraction studies indicate the formation of single phase structure at annealing temperature of 800°C. The crystallinity of the samples improved with the increase in film thickness (200–500 nm), however, structural changes were observed beyond film thickness 500 nm. The changes in surface morphology of the films have been discussed as a function of annealing temperature and thickness. Although well-defined Raman spectra were obtained at higher annealing temperature (≥700 °C) for low thickness film, low frequency Raman modes were observed for higher thickness film (≥500 nm). The optical transmittance of the film decreases with increase in thickness from 200 to 650 nm. The energy band gap and refractive index have been estimated as a function of annealing temperature and film thickness. The band gap values decreased from 4.38 to 3.88 eV with the increase in film thickness. The correlation between structural and optical properties has been done in order to optimize annealing temperature and film thickness at 800 °C/ 500 nm.

Synergistic effects of Zn B-site substitution in lead-free Ba0.95Ca0.05Ti0.92Sn0.08O3 ferroelectric ceramics for enhancing piezoelectric properties in energy harvesting applications

In this study, lead-free (Ba0.95Ca0.05)(Ti0.92Sn0.08)O3 (BCTS) and (Ba0.95Ca0.05)(Ti0.912Sn0.08Zn0.008)O3 (BCTS-Zn) ceramics with large piezoelectric properties were prepared via the conventional solid-state reaction. The effect of Zn B-site substitution on the structural, dielectric, ferroelectric, energy storage, electrocaloric and piezoelectric properties of BCTS ceramics were systematically investigated. X ray diffraction analysis and Raman spectroscopy of BCTS and BCTS-Zn ceramics confirm the formation of pure phase structure with the coexistence of orthorhombic, tetragonal and pseudo cubic phases at room temperature. The introduction of Zn into BCTS lattice resulted in a denser microstructure with larger average grain size which contributed in the enhancement of the dielectric constant maximum by ⁓35%. Furthermore, the substitution of Ti4+ with a small amount of Zn2+ (0.008) induced a shift in TR-O, TO-T and TT-C transitions towards higher temperatures in addition to an increase in the diffused phase transition character. Moreover, with Zn substitution, an amelioration in the maximum energy storage efficiency is observed from ⁓83% in BCTS ceramic to ⁓88% in BCTS-Zn ceramic. The electrocaloric properties were investigated using the direct and indirect methods. The highest value of the electrocaloric temperature change ΔT = 0.361 K at 319 K was calculated for BCTS ceramic using Maxwell approach with a relatively low electric field of 17.55 kV/cm. For BCTS-Zn ceramic, the enhancement of the piezoelectric properties (d33 = 420 pC/N, g33 = 23.02 mV/mN, FoM = 9.66 pm2/N) is attributed to the synergistic effect of the (O-PC-T) multiphase coexistence, large average grain size and high density of the ceramic. This study reveals that B site Zn substitution in BCTS lattice is an effective approach to improve the piezoelectric properties of the ceramic for energy harvesting applications.

Phase Equilibria and Structure Formation in the Polylactic-co-Glycolic Acid/Tetraglycol/Water Ternary System

This paper concerns a detailed study of the phase separation and structure formation processes that occur in solutions of highly hydrophobic polylactic-co-glycolic acid (PLGA) in highly hydrophilic tetraglycol (TG) upon their contact with aqueous media. In the present work, cloud point methodology, high-speed video recording, differential scanning calorimetry, and both optical and scanning electron microscopy were used to analyze the behavior of PLGA/TG mixtures differing in composition when they are immersed in water (the so-called "harsh" antisolvent) or in a nonsolvent consisting of equal amounts of water and TG (a "soft" antisolvent). The phase diagram of the ternary PLGA/TG/water system was designed and constructed for the first time. The PLGA/TG mixture composition with which the polymer undergoes glass transition at room temperature was determined. Our data enabled us to analyze in detail the structure evolution process taking place in various mixtures upon their immersion in "harsh" and "soft" antisolvent baths and gain an insight into the peculiarities of the structure formation mechanism active in the course of antisolvent-induced phase separation in PLGA/TG/water mixtures. This provides intriguing opportunities for the controlled fabrication of a wide variety of bioresorbable structures-from polyester microparticles, fibers, and membranes to scaffolds for tissue engineering.

Tuning band gap, structural and optical properties of tin selenide nanoparticles by alkali metal doping

The layered chalcogenide semiconductor, Tin monoselenide is an extraordinary candidate among chalcogenide materials because of their novel physical and chemical properties and tremendous applications in thermoelectrics, solar cells, energy storage devices, i.e. metal–ion batteries, supercapacitors etc. In this work, we synthesized polycrystalline SnSe by a simple hydrothermal method using sodium borohydride as a reducing agent for the single phase formation of SnSe nanostructures. X–ray diffraction spectroscopy has been done to confirm the orthorhombic structure and single phase formation. Fourier transform infrared characterization has been done to observe the linkage of groups among the precursors and solvents used. Further, Photoluminescence characterization has been done to estimate the band gap values and radiative recombination mechanism of the material. Ultraviolet–Visible (UV–Vis) spectroscopy has been used to study the optical properties of the material. Moreover, extrinsic heteroatom doping of sodium and potassium have been done to form NaxSnx-1Se and KxSnx-1Se respectively, which further decreases the band gap of the host material. The absorbance spectra, percentage of transmittance, extinction coefficient, direct band gap values depend upon photonic interactions and has been determined by UV–Vis spectroscopy. Elemental composition of each sample has been confirmed by EDX spectroscopy. All these properties have made the material a potential candidate for opto–electronic and photovoltaic applications.

Analysis of the formation mechanism of ceramic grains and mechanical properties of Mo2FeB2-based cermets by valence electron structure

The valence electron structures (VES) of Mo2FeB2-based cermets were constructed based on the empirical electron theory of solids and molecules (EET). The formation mechanism of grains and the influence of grain morphologies on the mechanical properties of the materials were explained in accordance with the calculated phase structure formation factors (S') and the interface electron structure (σN: the number of atom state groups, ∆ρ': electron density difference, and ρ': electron density), respectively. The results indicated that the morphologies of the Mo2FeB2 hard phase grains were reflected by the S' value of the distinct crystal planes. The progressive decrease in the Mo/B atomic ratio aggravated the differences between the S(210)' and S(001)' values and promoted the preferential growth of the hard phase grains along the [001] direction. This resulted in an increase in the (210)/(100) interface area, with the grains gradually forming an elongated structure. However, it was noticed that as the ratio of Mo to B increased, the value of |S(210)' − S(001)'| gradually tended toward 0, which allowed the elongated hard phase grains to transform into quasi-equiaxial grains. In addition, the maximum decrease in the σN value recorded was over 2500 when the Mo to B ratio increased continuously, indicating that the bonding strength at the (210)/(100) interface between the hard and binder phases was better at low Mo/B atomic ratios than at high Mo/B atomic ratios. This helped improve the fracture toughness and transverse rupture strength of the Mo2FeB2-based cermets.

Microstructure and Properties of Laser Cladding AlxFeCoCrNiMn High Entropy Alloy of Q345 Steel

High entropy alloy is a multi-component alloy material with equal or near atomic number, which has excellent wear resistance and corrosion resistance. In this paper, AlxFeCoCrNiMn (x = 0,0.5,1.0,1.5) high entropy alloy cladding layer was prepared by laser cladding on Q345 steel plate. The phase structure, microstructure, hardness and wear resistance of the cladding layer were studied. The results show that the cladding layer of AlxFeCoCrNiMn alloy has good metallurgical bonding ability with Q345 steel. The cladding area is mainly columnar and equiaxed. The cladding layer of AlxFeCoCrNiMn alloy is mainly composed of BCC + FCC solid solution phase, which is caused by the addition of Al element under the high entropy effect. Al element promotes the formation of BCC phase structure. With the increase of Al element, the hardness of cladding layer increases. The hardness of A1.0 cladding layer is 670HV, which is close to three times of Q345 steel. When Al (x = 1.0), the hardness of the cladding layer is the highest, and it also shows better wear resistance with lower friction and wear loss.