Formation Of Phase Research Articles

THERMOMECHANICAL COUPLED MODEL OF COATING SYNTHESIS ON A SUBSTRATE

Among modern combined laser and electron-beam technologies, special attention is paid to those in which composition formation takes place directly in the process of product creation or coating synthesis. In the present work, a coupled model of coating synthesis on a substrate is constructed. When building the model, a sequential transition was carried out from a three-dimensional model of the coating synthesis process on the substrate to a one-dimensional model, which is useful for qualitative analysis. The one-dimensional model takes into account the main physical features of the physical and chemical processes during the synthesis, as well as the coupled nature of the heat transfer and deformation at the same time taking into account the differences in thermophysical and mechanical properties of different materials. When constructing the intermediate analytical solution, it is assumed that the system "substrate-coating" is in a plane stress state. As a result, explicit expressions for the components of stress and strain tensors connected with changes in temperature and composition are obtained. With the help of the obtained analytical solution, the thermokinetic part of the problem is modified and reduced to a more convenient form. Further, the experience accumulated in the field of macrokinetics is used, which allows us to model the processes of creating new materials (e.g., intermetallic or metal matrix composites) in modern technologies from the point of view of controlling the processes of phase formation in the reaction zone by a moving external source. The transition to dimensionless variables revealed complexes and parameters representing relations of characteristic scales of different processes. The parametric study of the model allowed us to establish interesting qualitative effects. It is demonstrated that the quasi-stationary regime is accompanied by physical and chemical processes in the region, which the laser beam had left, due to the heat accumulated in the materials. It is shown that the coupled nature of different processes significantly affects the dynamics of synthesis and the parameters of the quasi-stationary regime.

Aging Treatment to Enhance Coercivity Through Grain Boundary Modification in SmFe10V2 Bulk Magnets

We explored the potential for an aging treatment to achieve high coercivity, of 0.859 MA/m, in a SmFe10V2 alloy with a ThMn12-type structure. Bulk magnets were fabricated by sintering ball-milled powders, followed by aging treatment. XRD and SEM analyses revealed that aging treatment promotes the formation of a Sm-rich grain boundary phase with nano-scale thickness. The high Sm content (~60–80 at.%) and low Fe content (~20–30 at.%) in the grain boundary phase led to non-ferromagnetism, enhancing the coercivity by isolating the 1–12 grains and weakening the dipolar interaction between the grains. The aging temperature and duration were optimized to maximize the Sm-rich phase and minimize the soft magnetic SmFe2 phase. This study provides a new fabrication method for ThMn12-type magnets and investigates the relationship between microstructure and coercivity, offering valuable insights for the future design and development of high-performance SmFe12-based magnets.

Assessment of Mechanical Behavior and Microstructure of Unsaturated Polyester Resin Composites Reinforced with Recycled Marble Waste

The quarrying and utilization of natural stones such as marble and granite are growing rapidly in developing countries. However, the processing, cutting, sizing, and shaping of these stones to render them functional generates huge quantities of waste and dust. These materials are often disposed of openly in the environment, and their potentially hazardous nature has negative repercussions on both the environment and human health. In this study, marble waste (MW) was used as a filler in the unsaturated polyester resin (UPR) matrix to enhance performance and characteristics while adding value to the waste and minimizing manufacturing costs. For this purpose, samples of UPR/MW composites were produced with 0, 5, 10, 15, and 20 wt.% of MW incorporated into the UPR. A full characterization that focused on the microstructure, thermal stability, and physical and mechanical properties was carried out. The results revealed that the use of 10 to 15% of MW improves mechanical performance, with increases from 17 to 26 kJ/m2, 14 to 17 MPa, and 794 to 1522 GPa in impact strength, tensile strength, and elastic modulus, respectively. By introducing a 20% MW filler, the composite loses its performance, particularly Shore D hardness, and becomes very brittle. Thermogravimetric analysis (TGA) indicated significant thermal stabilization, with a delay in the start decomposition temperature of 28 °C for 20 UPR/MW compared to 0 UPR/MW. Additionally, morphological and microstructural tests, namely, FT-IR, XRD, and SEM analysis, show a microstructural change, including the formation of crystalline phases, enhancing matrix-filler interactions due to the creation of Mg-O and Ca-O chemical bonds and the forming of filler agglomeration at high introduction rates that lead to defects in the microstructure. These results confirmed the mechanical results of the UPR/MW composites.

USE OF PULVERIZED COAL FUEL FOR PREHEATING SCRAP

Preheating of scrap in the converter is an actual area of ​​research in modern metallurgy. The growing requirements for energy efficiency and the reduction of raw material costs encourage the development of new technological solutions to increase the share of scrap metal in the charge of converter production. Traditional methods are often limited to the use of no more than 25% of scrap, which is associated with difficulties in its uniform heating and the possible formation of a liquid phase as a result of local overheating. The work evaluates the effectiveness of traditional and experimental technological solutions, such as two-tier and fuel-oxygen nozzles. The stages of ignition and burning of lump coal and pulverized coal fuel and their influence on the uniformity of scrap heating were studied. Experimental studies have shown that with a specific oxygen consumption of 1-1.35 m³/kg of pulverized coal fuel, uniform heating of scrap metal is ensured without the risk of melting the upper layers. During the use of a fuel-oxygen lance, the following features of heating scrap metal using pulverized coal fuel, which was blown in an oxygen ring shell, were discovered: - during the combustion of coal dust in an oxygen environment, due to the significant total surface of coal particles, the bulk of volatile СmНn does not have time to separate before the beginning particle ignition, and carbon burns at the same rate as volatiles. This contributes to the formation of high-temperature torches with great luminosity, which effectively affect the surface of the scrap; - the coefficient of use of blown oxygen and pulverized coal fuel is significantly higher than when using lump gas coal during heating of any duration. This is due to the greater luminosity of the formed torches, which contributes to the intensive absorption of thermal energy by the surface of the scrap; - the time required to heat the surface of the scrap metal to the specified temperature is reduced, which allows you to avoid the formation of a liquid component that can lead to undesirable consequences, such as uneven heating or damage to the converter lining. Based on the results of experimental studies, the relationship between the specific oxygen consumption and the flame temperature was established. The ability to control the temperature regime during the heating of scrap metal indicates the prospects of using a fuel-oxygen nozzle made of PVP to optimize the converter production process. For the full implementation of the technology, additional research and industrial testing are needed to optimize processes and increase production efficiency.

Structural, Magnetic, and Mössbauer Study on Nb and Heat Treatment of Fe-Si-B-P-Cu-Nb Ribbons

This study aims to enhance the amorphous formation ability and magnetic properties that are crucial for the production of high-quality nanocrystalline alloys. The structural, thermal, and magnetic characteristics of the alloy ribbons were analyzed through a systematic adjustment of Nb content, and, including Nb, significantly improved the amorphous formation ability and thermal stability of the alloy, which is vital for nanocrystalline production. By varying the Nb content within Fe85-xSi2B8P4Cu1Nbx (x = 0.0, 0.5, 1.0, and 1.5), we explored finer adjustments to achieve homogeneous amorphousness during the melt spinning process. Careful control over the Nb content facilitated the production of amorphous ribbons with consistent homogeneity, which was critical for the subsequent fabrication of nanocrystalline structures through heat treatment. As a result, the amorphous ribbon of Fe85.5Si2B8P4Cu1Nb0.5 showed a low coercivity of 7 A/m. The heat treatment showed a remarkably high saturation magnetic flux density of 1.94 T. Additionally, the grain size (D) decreased as the Nb content increased, with D values ranging from 25.09 nm to 24.29 nm, as calculated by the Scherrer formula. Mössbauer spectroscopy confirmed the formation of nanocrystalline and residual amorphous phases. The hyperfine magnetic field values (Beff) decreased from 25.7 T to 24.7 T in the amorphous samples and reached 33.0 T in the nanocrystalline phases. This study highlights Nb’s positive impact on thermal stability and amorphous formation capacity in Fe-Si-B-P-Cu alloys, culminating in the successful fabrication of nanocrystalline ribbons with superior structural and magnetic properties.

MOF-derived sheet-like E-Ru/Mo/Mo2C with Abundant Exposed Active Sites for Advanced Electrocatalytic Hydrogen Evolution

Abstract Abstract: A Ru/Mo/Mo2C sheet-structured composite electrocatalyst was synthesized through a meticulous methodology involving etching pretreatment with impregnation and subsequent calcination. This work delves into the intricacies of how the incorporation of Ru and the application of etching pretreatment influence the compositional makeup, morphological characteristics, electronic configuration, and, most notably, the hydrogen evolution reaction (HER) performance of the catalyst within the context of water electrolysis. Specifically, it was observed that the introduction of Ru catalyzed the formation of Mo and Mo2C phases, while the etching pretreatment played a pivotal role in augmenting the specific surface area of the catalyst, thereby facilitating the availability of an enriched landscape of active sites and modifying the electronic coupling between Ru and Mo species. Electrochemical evaluations revealed that the optimized E-Ru/Mo/Mo2C-3 catalyst exhibited remarkable HER kinetics, manifested by a minimal overpotential of 39.7 mV at a benchmark current density of 10 mA cm-2 and a favorable Tafel slope of 14.5 mV dec-1 in an alkaline medium. This comprehensive investigation offers profound insights into the rational design of metal-organic framework (MOF)-derived electrocatalysts, paving the way for the development of highly efficient HER catalysts tailored for water electrolysis applications.

Calcium aluminate cement: a study on the effect of additives for dental applications

Recent dental material advancements have sparked increased interest in dental cements due to their natural tooth-like appearance, biocompatibility, and stability. These cements hold potential in dental fillings, enamel and root protection, and connecting dental implants. However, no single cement fulfills all application needs, necessitating multiple types. Ideal dental cements require resistance to degradation, strong bonding, high strength, fracture toughness, and optical transparency for imaging. In this study, the effect of the addition of ZrO2, Bi2O3, and ZnO on the mechanical was the solid-state method was used for the synthesis of calcium aluminate (C3A) cement powder, and additives of zirconia, bismuth oxide and zinc oxide were added at magnitudes of 10 wt.% and 20 wt.%. X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), setting time, compressive strength (CS), Scanning electron microscopy (SEM) microscopy, and radiopacity evaluation (RE) were performed for characterization and properties evaluations. With the formation of a new phase, C3ZA2, the compressive strength increased by up to 275% by reducing porosity and stabilizing phase transitions during hydration. The evidence showed that the amount of bismuth oxide and zirconia additive have high optical (7 and 3.5 mmA) and biological properties and a significant impact on strength in dental applications.

Investigation of the impurity effect on the kinetics of thermal decomposition of natural gypsum at high temperatures

Natural gypsum is the most common sulfate on our planet, which is widely used in construction due to its excellent astringent properties, environmental friendliness, thermal and fire resistance, accessibility in nature and low price. Currently, the influence of modifiers, impurities and additives that can improve the strength, acoustic and thermal insulation characteristics of gypsum, which is so important in modern architecture, construction and reducing power consumption, is being increasingly studied. However, additives and impurities, controlled and uncontrolled, as in natural gypsum, can unpredictably affect the thermal stability and fire resistance of gypsum. The purpose of our work is to study the thermal characteristics of gypsum from various deposits in a wide temperature range. Our work shows that the temperature and rate of dissociation of gypsum directly depends on impurities that can change the process of its decomposition. As a result of the decomposition of natural gypsum with impurities, new phases are formed.It has been experimentally shown that the process of thermal destruction of gypsum with impurities has a complex multistage character, which is described by successive reactions of the nth order of the Avrami-Erofeev equation. It can be assumed that the reaction mechanism consists in the rapid formation of numerous nucleation centers on the surface of solid anhydrite. Kinetic parameters of thermal decomposition of gypsum of complex composition and phase formation at high temperatures are calculated. This experimental study shows the dependence of thermal stability on the amount and grade of impurities in gypsum. The results obtained contribute to the improvement of the basic concepts of the mechanism of decomposition of gypsum, as well as the explanation of some high-temperature phase formation processes in nature.

Outstanding electrocatalytic activity and corrosion property of NiCr nanoparticle alloys electrodeposited from a choline chloride/urea deep eutectic solvent

Nickel-chromium alloys are known for their superior corrosion resistance, wear resistance, and hardness, making them a topic of significant interest. This study explores the electrodeposition of Ni-Cr alloys onto a glassy carbon electrode from a choline chloride/urea deep eutectic solvent. Electrochemical techniques, including cyclic voltammetry and chronoamperometry, were utilized to explore the deposition process. Voltametric analysis revealed that Ni-Cr alloys could be electrodeposited from the reline DES through a single potential step. The analysis of current density transients indicated that the electrocrystallization of Ni-Cr follows a three-dimensional (3D) nucleation and diffusion-controlled mechanism on the bimetallic growing surface. Additionally, the presence of the Ni(II) component was found to significantly enhance the kinetics of Ni-Cr phase formation, facilitating rapid deposition from the eutectic mixture. Surface characterization techniques, including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX) mapping, and X-ray diffraction (XRD), confirmed the uniform distribution of elements, the formation of the Ni-Cr phase, and its crystalline structure. The high quality of nickel-chromium alloys obtained from DES highlights their potential applications in various engineering fields, particularly in surface coating and metal protection.

Ultrasonic chemical synthesis of zinc-manganese ferrites with improved magnetic properties

Zinc-Manganese spinel ferrites (Zn1-xMnxFe2O4) are nowadays very attractive magnetic materials for cancer diagnostic and therapy. With the help of intense ultrasonic waves, sonochemical synthesis method was used to prepare stoichiometric and chemically homogenous nanoparticles by varying the manganese content. The crystal structure along with the size and shape of the as-prepared nanoparticles were described using XRD, TEM and FT-IR techniques, while cations distribution was carefully investigated using XPS and Mössbauer spectroscopic techniques and supported with density functional theory calculations. The crystal structure study revealed the presence of a pure single cubic spinel phase, where the unit-cell and the size were observed to decrease as the manganese incorporation was increased with clear indication of cationic redistribution and degree of inversion variations. Due to the very small variation of the total energy between different configurations, the probability of formation of a mixed phase was found to be very high in such a way that the more mixed was the phase, the more stable it was. A relevant fact was the noticed quasi-systematic ionic exchange made possible by the very short reaction times and high energy offered by the ultrasonic waves. For manganese concentrations up to 60%, the systematic ionic process started by incorporating manganese ions into octahedral sites and pushing iron ions to migrate and replace those of zinc in tetrahedral sites. Such an ionic movement was of central importance for the improvement of the magnetic properties due to the establishment of super-exchange interactions. Such an ionic engineering should definitely open the way to promising applications in biomedical imaging.

Sustainable stabilization/solidification of electroplating sludge using a low-carbon ternary cementitious binder

Electroplating sludge (ES), due to its high dosages of heavy metals (HMs), is classified as hazardous waste, presenting risks to both health and environment. Stabilization/solidification (S/S) technology is extensively applied in ES treatment. This study designs a low-carbon ternary cementitious binder, limestone calcined clay cement (LC3), for S/S treatment of ES and investigates the immobilization mechanism of HMs in the crystalline products and calcium alumino-silicate hydrate (C-A-S-H) within LC3. Results show that CrO42- and Cd2+ are primarily stabilized in aluminate crystalline products by replacing SO42- and Ca2+ in the double-layered plate structure, respectively. The remaining CrO42- is captured by the (SiOOH)2AlCa⁺ groups in C-A-S-H generated from substitution of aluminum tetrahedra to bridging silicon tetrahedra. For positively charged Cd2+, it is mainly stabilized through ion exchange with Ca2+ on the C-A-S-H chains. The pozzolanic reaction of calcined clay increases the Al/Ca and Si/Ca atomic ratios in C-A-S-H, enhancing the immobilization efficiency of C-A-S-H to CrO42- and Cd2+. The synergistic effect of calcined clay and limestone, along with the dissolution of aluminosilicates in calcined clay, changes the structure and composition of hydration products, facilitating the chemical binding of CrO42- and Cd2+ by aluminate products. Moreover, the extra hydration products generated by the pozzolanic reaction and the formation of numerous carboaluminate phases strengthen the physical encapsulation performance to HMs. Regarding actual S/S performance, multi-scale evaluation results show that the designed LC3 binder achieves sustainable S/S of ES with high strength, low carbon emission, low cost, and low energy consumption.

Boosting nickel nanoferrite’s specific capacitance with Azadirachta Indica for advanced supercapacitors

Nickel Ferrite (NiFe2O4) a valuable transition metal oxide possessing a spinel structure, it is extensively utilized in industry due to its compelling properties. In this present study the sol–gel auto-combustion synthesis method was employed using nitrates and citric acid in conjunction with double distilled water (DDW) and Azadirachta Indica extract. The X-ray diffraction (XRD) analysis revealed the formation of a cubic spinel phase with high crystallinity. Crystallite size of prepared Nickel Ferrite in double distilled water and Azadirachta Indica by Scherrer’s equation and Williamson-Hall plot (W-H) are 28.09 nm and 33.01 nm as well as 16.23 nm and 16.55 nm, with microstrains of 0.32739 % and 0.339 × 10−3 % respectively. The notable reduction in the crystallite size is observed when employing Azadirachta Indica compared to the double distilled water-based synthesis. The X-ray density of the synthesized sample in double distilled water and Azadirachta Indica are obtained as 3.935 (g cm−3) and 5.427 (g cm−3). Transmission electron microscopy (TEM) of Azadirachta Indica-based nanostructured Nickel Ferrite material exhibited a particle size of 17.06 nm. The study encompassed the calculation of various parameters such as hopping lengths, polaron radius, specific surface area, packing fraction, and dislocation density. Magnetic parameters are comprehensively examined using a vibrating sample magnetometer (VSM), revealing a Bohr magneton is 3.278. The shifting of coercivity curve observed towards right due to exchange bias effect and the unidirectional anisotropy for diamagnetic Azadirachta Indica based Nickel ferrite. Optical properties are investigated through UV–VIS and Fourier-transform infrared (FTIR) spectroscopy, resulting in a band gap energy of 1.75 eV and a porosity is 11.16 %. Electrochemical evaluation of Nickel Ferrite electrodes is conducted over a potential range from 0.0 to 1 V. The specific capacitance of Nickel Ferrite electrodes synthesized with double distilled water and Azadirachta Indica are determined as 511.9 F/g and 695 F/g respectively, at a scan rate of 50 mV/s, as evaluated through cyclic voltammetry (CV) measurements in Ag/AgCl (0.1 M NaOH as electrolyte). The specific capacitance of Nickel Ferrite, produced with double distilled water and Azadirachta Indica extract, is 686 F/g and 817.398 F/g respectively, as determined by Galvanostatic charge–discharge (GCD) measurements. The study conclusively demonstrated significantly improvement in the electrochemical performance of Nickel Ferrite, synthesized with Azadirachta Indica extract for supercapacitor application. Based on GCD and CV, the specific capacitance has been boosted significantly with Azadirachta Indica extract for supercapacitor application.

On the Synergistic Interplay Between Annealing Temperature and Time and Additive Concentration for Efficient and Stable FAPbI3 Perovskite Solar Cells

Formamidinium-based lead triiodide perovskite (FAPI) is the workhorse candidate for highly efficient perovskite solar cells owing to its ideal bandgap and phase purity. An essential condition to that is the formation of a pure α-black phase, commonly triggered by external additives such as methylammonium chloride (MACl). This results in the suppression of unwanted crystallization phases and defect reduction. However, there is no consensus on the exact experimental conditions (i.e. annealing time, temperature and concentration) for processing of the additives neither a defined relationship between them nor the resulting film morphology, leading to scattered knowledge on it and lack of thin film reproducibility. Here, we provide a systematic investigation on the simultaneous effect of MACl concentration, annealing time, and annealing temperature on the FAPI crystallization, and ultimately FAPI perovskite solar cell efficiency and stability. Finally, the optimized combination of such parameters, based on tests with 230 devices, leads to the realization of 22.7% efficient inverted FAPI perovskite solar cells with enhanced stability.

Evolution of the liquid/solid interface roughness in Si1-xGex layers processed by nanosecond laser annealing

Pulsed laser annealing is a relevant alternative to conventional thermal processes for future technology nodes as it enables the application of a fast and local thermal budget. Such high-energy process can lead to the formation of a liquid phase that recrystallizes upon heat dissipation, through a high velocity liquid/solid interface moving towards the surface. Here, we report on the evolution of the liquid/solid interface roughness and its influence on the crystallinity of Si1-xGex layers depending on multiple parameters (strain state, doping level, Ge content, and pulse duration). This has been conducted with a roughness quantification method based on cross-section STEM-HAADF micrographs. It has been established that the liquid/solid roughness can be decreased by: (i) a compressive strain decrease, (ii) the use of short duration laser pulses or (iii) a reduction of the initial Ge content. The Ge content and strain must correspond to suitable values for optimized MOSFET performances. Consequently, strain and pulse duration were found to be pertinent levers for liquid/solid interface roughness reduction. Increasing the amount of boron atoms in s-Si1-xGex:B/Si systems is another relevant strategy, as compressive strain decrease would then be associated with a beneficial contact resistance lowering in the source-drain regions of p-type MOSFET devices.

Effect of Fe Addition on Microstructure and Properties of Al-3Ni Alloys

Al-Ni alloys exhibit superior castability and thermal stability, making them potential substitutes for Al-Si based alloys for heat dissipation and heat resistance applications. This research comprehensively investigates Al-Ni-Fe alloys, focusing on the impact of Fe content on the microstructure and thermal and mechanical properties of Al-Ni alloys. The results reveal that introducing Fe ranging from 0 to 0.6% leads to the formation of a lamellar Al9FeNi phase characterized as a ternary eutectic in Al-3Ni alloys (L→α-Al+Al3Ni+Al9FeNi). As these Fe concentrations, Al-3Ni alloys exhibit a modest decrease in thermal conductivity, accompanied by a significant improvement in strength. Beyond 0.6% Fe, the Al9FeNi phase forms a coarse lamellar structure prior to the ternary eutectic reaction, significantly decreasing thermal conductivity, curtailing ductility, and shifting the fracture mechanism from ductile to brittle. Notably, the Al-3Ni-0.6Fe alloy stands out with superior comprehensive performance, achieving thermal conductivity, tensile strength, and elongation of approximately 189Wm-1 K-1, 168MPa, and 19%, respectively. This alloy comprises the primary α-Al and (α-Al+Al3Ni+Al9FeNi) eutectic structure. This finding emphasizes the importance of precisely controlling Fe content and the morphology and distribution of Al9FeNi to optimize the performance of Al-Ni-Fe alloys. This paper provides a solid theoretical and experimental foundation for developing Al-Ni-Fe alloys in heat dissipation technologies.

Improving properties of Portland cement-blast furnace slag blended paste through sodium bicarbonate-induced carbonation

The addition of NaHCO3 has the potential to enhance properties of concrete by facilitating internal carbonation. This study investigates the effects of the incorporation of NaHCO3 into ordinary Portland cement-blast furnace slag paste. The results show that the addition of NaHCO3 had an impact on the hydration process and increased the heat of hydration on all the slag samples. NaHCO3 caused internal carbonation and facilitated the formation of calcium carbonate and different carbon-based AFm phases, such as monocarbonate. The incorporation of NaHCO3 improved the pore structure of the paste and enhanced resistance against chloride penetration. The chloride migration coefficient of the Portland cement paste sample was reduced up to 96.5% with the incorporation of 2% NaHCO3 at 70% slag replacement. The compressive strength of the samples also showed an improvement with 1% NaHCO3 addition increasing the early age strength and 2% NaHCO3 addition increasing the matured age strength.

Impact of Self-Assembled Monolayer Structural Design on Perovskite Phase Regulation, Hole-Selective Contact, and Energy Loss in Inverted Perovskite Solar Cells

Recent studies have shown that self-assembled molecule (SAM)-based hole-selective contacts (HSCs) offer a promising solution to the challenges faced by perovskite solar cells (PVSCs), including minimal material consumption, scalable production, high interface stability, and the use of environmentally friendly solvents. In this study, the efficacy of two designs of SAMs (Cz and PA) as HSCs in inverted PVSCs was investigated by comparing them with the conventional MeO-2PACz (MeO) SAM. Surface analyses showed that the surface of PA is smoother than that of Cz, which helps to reduce interfacial defects. Subsequent perovskite deposition exhibited a reduced formation of the PbI2 phase, incidiating that its phase modulation ability is superior to that of MeO. Further analyses demonstrate the superior charge extraction ability of PA as a result of reduced interfacial defects and non-radiative recombination at the HSC/perovskite interface. By further coupling with phenethylammonium iodide (PEAI) surface passivation, both interfaces of the perovskite film were optimized and the inverted ((FAPbI3)0.85(MAPbBr3)0.15)0.95(CsPbI3)0.05 (bandgap = 1.62eV) PVSC achieves a high power conversion efficiency (PCE) of 23.3% and a very high open-circuit voltage of 1.227V due to the largely reduced energy loss. In addition, the PA PVSC exhibits enhanced long-term thermal stability at 85°C in a nitrogen atmosphere.

Dielectric Characteristics of Iridium Substituted Co0.05-xTi0.95O2 Dilute Magnetic Semiconductors for Electrical Device Applications

In the current study, a cost effective solid-state method have been used to prepare iridium (Ir) substituted and cobalt doped titanium dioxide (TiO2) dilute magnetic semiconductors (DMS) materials {i.e.; IrxCo0.05-xTi0.95O2; 0.00 ≤ x ≤ 0.05 DMS}. The impact of Ir substitution on structural, optical and dielectric properties for the prepared IrxCo0.05-xTi0.95O2; 0.00 ≤ x ≤ 0.05 DMS samples have been investigated using X-ray diffractometer, ultraviolet-visible spectroscopy and LCR (inductor, capacitor and resistor) meter, respectively. The structural analysis confirms the tetragonal rutile phase formation with space group p42/mnm-136, while the values of band gap energy increase with increasing Ir concentrations in prepared DMS materials and band gap value approaches the band gap energy of void band gap materials for large applications. The dielectric constant and tangent loss have been studied as a mapping of frequency (20Hz - 20MHz) at room temperature. Both the dielectric constant and tangent loss linearly decrease with increase in applied frequency and become stable at high frequency values, therefore, these DMS materials could be beneficial for storage and electrical device applications.

Pressureless synthesis and consolidation of the entropy-stabilized (Hf0.25Zr0.25Ti0.25V0.25)B2-B4C composite by ultra-fast high-temperature sintering (UHS)

Entropy-stabilized Ultra High-Temperature Ceramics (UHTC) offer a groundbreaking solution to the challenges of extreme environments, showcasing enhanced mechanical properties, thermal stability, and resistance to oxidation at high temperatures. The consolidation of UHTC by ultra-fast high-temperature sintering (UHS) significantly reduces processing times and temperature and can produce dense high-performance ceramics with superior mechanical properties. This study reports the pressureless synthesis and consolidation of the entropy-stabilized (Hf0.25Zr0.25Ti0.25V0.25)B2-B4C composite through UHS within 1minute, starting from transition metal diboride powders. B4C acts as an effective sintering aid, promoting the densification of the system and the formation of a nearly single-phase hexagonal diboride with a diboride-eutectic phase. Furthermore, a secondary minor hexagonal phase rich in V and Zr is formed close to the eutectic regions. Sintering currents of 40A were necessary to reach densities higher than 90% under pressureless conditions, achieving nano hardness higher than 27.3GPa, comparable with high-entropy diborides produced by Spark Plasma Sintering. The study highlights the entropy-stabilized phase formation, diffusion, densification, and grain mechanisms involved during UHS. The work contributes to understanding entropy-stabilized ceramics produced by UHS as a faster and less energy-consuming process than more conventional sintering methods.

Synthesis and Characterization of Ni2+- Zr4+ Doped Ba-Ca M-Type Hexaferrites using Sol-Gel Auto-Combustion Method

This work aims to study the effect of Zr-Ni dopant on the structure and traits of M-type barium calcium hexaferrites (BaCaM). For the first time, Ba0.8Ca0.2ZrxNixFe12-2xO19 (0.0≤ x ≤1.0) samples are synthesized employing the SGACM (sol-gel auto-combustion method). The pure phase formation of BaCaM was established by XRD data Rietveld refinement. An augmentation in both the lattice parameters (‘a’ as well as ‘c’) owing to the higher ionic radii of dopant ions as compared to Fe3+ shows that Ni2+ and Zr4+ions were successfully swapped with Fe3⁺. The "c/a" ratio lies between 3.93-3.96 disclosing that the synthesized materials possess an M-type hexagonal ferrite structure. The reduction in crystallite with an increase in doping level might be due to lattice strain generated by the larger size of Ni2+ and Zr4+ dopant ions. The presence of two bands in the wavenumber range of 400 to 880 cm-1 in FTIR spectra corresponds to the Fe–O stretching in octahedral and tetrahedral locations. The Raman peaks widen without any shifting of the peak with an increment in Ni2+-Zr4+ ions contents revealing that Ni2+-Zr4+ are incorporated into BaCaM without changing its crystal structure. According to the M-H plots Ms value enhance from 24.94 (x= 0.00) to 36.84 emu/g (x= 0.60) and beyond x=0.60, Ms values drop with an increment in Ni2+-Zr4+substitution level. A broad coercivity range lies between 4858 Oe (x = 0.0) to 653 Oe (x = 1.0), decreasing monotonically with substitution in Ni2+-Zr4+. All the synthesized material exhibits a reduction in dielectric constant value as frequency increases. Ni-Zr-doped BaCaM materials could be a suitable candidate for magnetic recording media and microwave absorber applications.