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In this work, we have employed the first-principles calculations to investigate the phase stability and mechanical and optoelectronic characteristics of Hf2AX (A=Al, Si and X=C, N) MAX phases. Phase stabilities of Hf2AX compounds have been evaluated by the formation enthalpy computations and phonon dispersion curves, which indicate that all studied compounds are structurally and dynamically stable. The mechanical stability has been determined by elastic stiffness constants, which confirms that the studiedMAX phases aremechanically stable. The computed results for Pugh's and Poisson ratios indicate the brittle nature of Hf2AX MAX phases. It is interesting to note that Si-based MAX phases possess high values of B/G, indicating that they are harder than Al-based compounds. The obtained band structures and partial density of states indicate the metallic character of all Hf2AX compounds. The strong hybridization of d-orbitals of Hf with p-orbitals of N and the comparatively weaker hybridization of p-orbitals (Hf) with Al/Si p-orbitals is observed. The presence of pseudogaps near the Fermi energy level emerges due to the orbital hybridization involving Hf, Al/Si, and C/N atoms. The analysis of charge density difference maps reveals the presence of a strong covalent bond between the Hf and C/N atoms, whereas a relatively weaker covalent bond is seen between the Hf and Al/Si atoms. Furthermore, numerous optical characteristics have been investigated to account for the behavior of the Hf2AX compounds to those of impinging electromagnetic rays. The highest absorptivity is noticed within the energy range of 7.5-12.5 eV. The optical spectra in the range of 1.7 eV (IR) to 9 eV ultraviolet (UV) have been observed for the investigated MAX phases, predicting their suitability as proficient energy absorbers within the UV region. The Intriguing properties of Hf2AX compounds are anticipated to be appropriate materials for a variety of applications. [ABSTRACT FROM AUTHOR]

This study explores the effects of porosity as well as nonlocal parameter on both low- and high-frequency free vibration behaviors of functionally graded nanoplates for the first times. Three distinct models are used to describe porosity distribution. A combination of the six-unknown quasi-3D theory is utilized to define the displacement field of the nanoplates. The Hamilton's principle is exploited in combination with the nonlocal elasticity theory to establish the governing equations of the motion of the functionally graded nanoplates. The influence of some parameters such as geometric, power-law index, porosity, and nonlocal parameter on the free vibration behaviors of the functionally graded porous nanoplates is explored in detail. This pioneering study unveils a wealth of numerical findings that, for the first time, shed light on the intricate high-frequency behaviors exhibited by these nanoplates. These insights not only expand the scientific understanding of functionally graded porous nanoplates but also offer valuable knowledge that can empower scientists and engineers in their pursuit of designing and optimizing nanostructures in this domain. This research marks a significant milestone in the study of nanoplates, bridging the gap between low- and high-frequency vibration analyses and opening new avenues for future research and practical applications. [ABSTRACT FROM AUTHOR]

Aluminum 6061 alloy using silicon carbide (SiC) particles as a reinforcement is a promising metal matrix composite (MMC) that has gained significant attention in the automotive and aerospace industries. Till now the effect of the addition of SiC particles in Al6061 composite is not studied in depth and also very few studies are reported the on‐wear properties of Al6061‐SiC composite. So, to further enhance the properties of Al6061 alloy and to study in depth this work is carried out. In this study, MMCs are prepared using the stir casting route with varying weight fractions (5–10 wt%) of SiC particles. The properties of composites including tensile strength, compression strength, and wear are evaluated experimentally. The results demonstrated that the incorporation of SiC particles into the Al alloy matrix leads to a notable improvement in mechanical and wear parameters. The tensile and compression strength of the Al composites increases with an increase in the weight percentage addition of SiC particles (from 5% to 7.5%). At 7.5 wt% addition of SiC, it is found that the particles are uniformly distributed throughout the Al6061 alloy matrix. And also shows higher mechanical and wear properties as compared to 5% and 10% addition. [ABSTRACT FROM AUTHOR]

In this study, we investigate the structural, electronic, magnetic and mechanical properties of the Na-based half-Heusler alloys XYZ composed of X=Na ( p 0 atom); Y=K, Rb, Cs ( d 0 atoms) and a main body sp atom Z=C, Si, Ge, Sn, Pb by using the DFT based full-potential WIEN2k package. We compare the total energy vs volume of ferromagnetic, antiferromagnetic and non-magnetic half-Heusler structures to obtain the stable magnetic structure. Calculations show that compounds are stable in the half-Heusler β -phase and the ferromagnetic state. From 15 alloys under study, 13 of them showed half-metallic behavior in the minimum-energy half-Heusler phase at the optimized lattice constant. We show that all compounds have the same total magnetic moment equal to 2 μ B . The band structure and the density of states of half-Heusler alloys are obtained. The elastic constants C 11 , C 12 and C 44 of the single crystal and the related elastic moduli G, B, E, υ of the polycrystalline aggregates are also calculated and used to study the mechanical stability of these alloys. Furthermore, the average, transverse, longitudinal sound velocities and the Debye temperature for these compounds are calculated. Finally, the Curie temperatures T C of the half-Heusler alloys are estimated by using the mean field approximation. The estimated Curie temperatures shows that these compounds preserve the ferromagnetic state and magnetic polarization at temperatures much higher than the room temperature and may be suitable for spintronic applications. [ABSTRACT FROM AUTHOR]

Driven by the development of energy storage systems (EESs), finding alternative anode materials forlithium‐ion batteries to replace the general carbon materials is becoming a hot research topic in the world. Using the metal oxides, metal sulfides, metal phosphides, metal selenides belonging to the conversion type and Sn, Sb, Bi, Ge, P and Si belonging to the alloy storage type seems to be a preferred option. Nevertheless, the demerits such as volume expansion and bad conductivity of alternative materials restrict their practical application. Carbon covering is an efficacious strategy to deal with the aforementioned issues because it can restrict the volume expansion and improve the conductivity of the composite materials effectively. This present review paper comprehensively describes the suitable carbon resources and preparation methods for expanding the practical applications of materials belonging to the conversion type and ally type in fabrications of negative electrodes. [ABSTRACT FROM AUTHOR]

Bismuth oxide (Bi2O3) nanoparticles are synthesized and evaluated for their function as materials for solar cells. Bi2O3 solution is inexpensively produced from the Nigella sativa seeds using a green synthetic method. The synthesized Bi2O3 solution is deposited by droplet casting method, and the synthesized nanofilm is dried at 80°C. Subsequently, diagnostic tests such as UV–VIS, XRD, and FTIR are performed on the Bi2O3/glass thin films. By means of the SEM, EDS, AFM, and I–V characteristics in dark and under illumination, the optical and structural characteristics of Bi2O3- nanoparticle films are investigated to determine the optical energy gap and crystalline material. X-ray diffraction reveals the presence of a tetragonal crystal system in the phase. The estimated band-gap energy Eg is approximately Eg1 = 3.6 eV, and FTIR analysis shows the degree of infrared absorption as a function of wavelength to demonstrate the presence of functional groups in bismuth-oxide molecules from Bi–O bonds. SEM–EDS morphology studies examine the occurrence of nanocrystals of various shapes and sizes. Finally, as a bulk heterojunction device, the I–V performance of the solar cell (Ag/Bi2O3/PSi/Si/Ag) deserves attention, and a fill factor FF= 48 is found for a solar-cell efficiency of 2.8%, ideality factor β= 1.35, characterization resistance RCH = 175 Ω, and the parallel resistance = 25.14 Ω·s. This cheap nanoparticle material could be an ideal candidate for future energy applications. [ABSTRACT FROM AUTHOR]

The casting structure of the AA6063 alloy contains intermetallic particles of β-Al5FeSi, which can result in the fragility of the cast pieces. However, with heat treatment, the β phase transforms from a needle or plate form into an intermetallic phase known as α, which resembles Chinese-script in its morphology. To analyze the effect of the ratio of Fe/Mn with different ratios of 0.5, 0.75, and 1, a heat treatment process is used with intermittent interruptions. The alloy is subjected to a temperature of 575 °C for 12 h to determine the microstructural evolution of the β-Al6FeMn and α-Al15(FeMn)3Si2 phases. This study used scanning electron microscopy to conduct point analyses and elemental mappings of the intermetallics found in the casting and heat treatment samples. Additionally, X-ray diffraction was employed to determine the stoichiometry of the present phases. The results indicated that the cast structure contains β-Al6FeMn and α-Al15(FeMn)3Si2 phases and that the β-Al6FeMn phase transforms into the α-Al15(FeMn)3Si2 phase upon completion of the heat treatment process. By using specific Fe/Mn ratios, the formation of the needle-shaped Al5FeSi phase in the casting structure of the alloy can be inhibited, leading to the precipitation of phases such as β-Al6FeMn and α-Al15(FeMn)3Si2 instead. [ABSTRACT FROM AUTHOR]

The topological and chemical short-range ordering (TSRO and CSRO) of Pd82Ge18 amorphous alloys prepared by the single-roll liquid quench method were analyzed using a combination of anomalous X-ray scattering and reverse Monte Carlo (RMC) simulation. The degree of development of TSRO and CSRO in the amorphous structure model made with the RMC simulation (RMC model) was evaluated by comparison with the dense random packing model (DRP model) calculated using metallic and covalent atomic radii. In the RMC model, a shortening of the Pd--Ge nearest neighbor correlation and a decrease in the coordination number around Ge were observed. Voronoi polyhedral analysis was performed to evaluate the local geometrical structure around the Pd and Ge atoms. Although the DRP structure can reasonably approximate the local structure around the Pd atoms, the TTP structure corresponding to the local structure in crystalline Pd2Ge develops around the Ge atoms as a characteristic TSRO. However, the preferential coordination of Pd atoms around Ge, which is a CSRO associated with the TTP structure in the crystalline phase, was not observed. These results indicate that strong CSRO does not necessarily accompany the TTP structures in metal-semimetal amorphous alloys. [ABSTRACT FROM AUTHOR]

Inclusions in metallurgical grade silicon (MG-Si) can significantly degrade the quality and performance of silicon materials. Thus, it is essential to implement effective measures to control and minimize their presence. This study investigates the morphology, distribution, and microstructural evolution of inclusions in silicon by introducing varying amounts of Sn. The changes in Fe content at different positions in silicon ingots before and after Sn refining were examined. The study demonstrates that Sn refining can reduce the number of inclusions at the bottom of silicon ingots by up to 71.3 pct. The morphology of inclusions undergoes a transition from fine filaments and sporadic dots to block-like formations, ordered short rods, and dots. There is an upward migration of Fe in the vertical direction, leading to a reduction in Fe content at the bottom from 0.61 to 0.25 pct, representing a significant decrease of 59.03 pct. These findings suggest that the addition of Sn to silicon can effectively remove Fe impurities. Additionally, the incorporation of Sn refining enables a reduction in the formation of the Si7Al8Fe5 phase and enhances the selectivity of the organosilicon monomer synthesis process. Remarkably, the partial substitution of Ti by Al leads to the formation of the FeSi2Ti(Al) phase. However, Ca tends to concentrate in Sn and remains unaffected by the Sn content. These empirical findings offer experimental evidence for effectively reducing and controlling the quantity and morphology of inclusions in MG-Si, thereby significantly enhancing the quality of MG-Si production. [ABSTRACT FROM AUTHOR]

The arsenic adsorption performance of silicon (Si), iron (Fe), and magnesium (Mg) mixed hydrous oxide containing a Si: Fe: Mg metal composition ratio of 0.05:0.9:0.05 (SFM05905) was investigated. SFM05905 was synthesized by the co-precipitation method. Batch experiments on arsenic adsorption were conducted at various temperatures and concentrations. Adsorption isotherms models were represented by a linearized equations and were insensitive to temperature change. The anion selectivity of SFM05905 at single component was high for arsenite (III), arsenate (V), and phosphate (PO4), indicating that PO4 inhibits arsenic adsorption. The adsorption amount of As (III), As (V), and PO4 were compared using a column packed with granular SFM05905, and an aqueous solution was passed by a combination of several anions that are single, binary, and ternary adsorbate systems. As (III) had the highest adsorption amount; however, As (III) and PO4 were affected by each other under the ternary mixing condition. Although the adsorption amount of As (V) was smaller than that of As (III), it was not affected by other adsorbates in the column experiments. Finally, although the adsorption of both arsenic continued, the adsorbed PO4 gradually desorbed. [ABSTRACT FROM AUTHOR]

Al-Si alloys of hypoeutectic, near-eutectic, and hypereutectic compositions, prepared from commercial pure aluminum and silicon, were investigated to study their tensile and compressive properties. The microstructures in as-cast stage were found to be refined after subsequent remelting and casting for two, five, and ten cycles. The proportion of eutectic phase and silicon particles increased with silicon content and influenced the nature of stress–strain curves. Both tensile and compressive stress–strain curves exhibited increase in flow stress with increasing strain, which could be expressed by Hollomon type relationships, but the tensile deformation occurs at lower flow stress than that in compression. While tensile specimens showed limited elongation to failure, the compression ones exhibited larger strains, up to 30% without failure. The tension–compression flow asymmetry was noted to vary as a function of the number of remelting cycles and of the silicon content in the alloy. The work hardening rate showed only stage III behavior in tension but both stage III and IV behavior in compression. The flow stress, including the yield strength, in compression was found to increase with decrease in grain size. However, in tensile deformation, instead of grain size effect, the yield strength was noted to increase with the decrease in inter-particle spacing. In both these cases, the Hall–Petch type relationships were found to be obeyed. [ABSTRACT FROM AUTHOR]

In conventional hot stamping, an Al-Si-coated blank is first heated above the austenitization temperature and then soaked for a period of time within a furnace, prior to the stamping operation. In this work, the impacts of furnace heating rate, soaking temperature, and soaking time on the Al-Si coating evolution were investigated for two commercial coating weights, 80 and 150 g/ m 2 . These heat treatment parameters during heating and soaking affect the coating microstructure and the thickness of the interdiffusion layer, which affect the properties of the as-formed coatings. The transformation and growth of binary Fe-Al and ternary Fe-Al-Si intermetallic layers were characterized and quantified for soak times up to 240 s. The results show that the effect of the heating rate on the Al-Si intermetallic distribution and ternary phase morphology was more severe than the soaking time and soaking temperature. The F e 2 A l 5 (η) phase was the dominant layer at the beginning of the soaking stage with a F e 3 A l 2 S i 3 ( τ 1 ) layer formed within it, and then the F e 3 A l 2 S i 3 layer transformed into F e A l ( β 2) as the soaking time increased due to the interdiffusion of Fe and Al. The transformation of F e 3 A l 2 S i 3 to F e A l occurred at a higher rate for elevated soaking temperatures due to the greater diffusivity of Al and Fe. The interdiffusion layer (IDL) consisted of F e A l , F e 3 A l ( β 1) and α − F e . Higher soaking temperatures of 1000 °C resulted in a thicker IDL for the same soak time when compared with 900 °C and 950 °C, but when the heating rate was lower, the IDL was thicker than that at the higher heating rate since a longer heating time was required to reach the soaking temperature of 900 °C, which prolonged the diffusion time during the heating stage. The findings were similar for AS80. [ABSTRACT FROM AUTHOR]

A true monolithic infrared photonics platform is within reach if strain and bandgap energy can be independently engineered in SiGeSn semiconductors. Herein, we investigate the structural and optoelectronic properties of a 1.5 μm-thick Si0.06Ge0.90Sn0.04 layer that is nearly lattice-matched to a Ge on Si substrate. Atomic-level studies demonstrate high crystalline quality and uniform composition and show no sign of short-range ordering and clusters. Room-temperature spectroscopic ellipsometry and transmission measurements show direct bandgap absorption at 0.83 eV and a reduced indirect bandgap absorption at lower energies. Si0.06Ge0.90Sn0.04 photoconductive devices operating at room temperature exhibit dark current and spectral responsivity (1 A/W below 1.5 μm wavelengths) similar to Ge on Si devices, with the advantage of a near-infrared bandgap tunable by alloy composition. These results underline the relevance of SiGeSn semiconductors in implementing a group IV material platform for silicon-integrated infrared optoelectronics. [ABSTRACT FROM AUTHOR]

Ge/SiGe multi-quantum well heterostructures are highly sought-after for silicon-integrated optoelectronic devices operating in the broad range of the electromagnetic spectrum covering infrared to terahertz wavelengths. However, the epitaxial growth of these heterostructures at a thickness of a few micrometers has been a challenging task due to the lattice mismatch and its associated instabilities resulting from the formation of growth defects. To elucidate these limits, we outline herein a process for the strain-balanced growth on silicon of 11.1/21.5 nm Ge/Si0.18Ge0.82 superlattices (SLs) with a total thickness of 16 μm corresponding to 500 periods. Composition, thickness, and interface width are preserved across the entire SL heterostructure, which is an indication of limited Si–Ge intermixing. High crystallinity and low defect density are obtained in the Ge/Si0.18Ge0.82 layers; however, the dislocation pileup at the interface with the growth substrate induces micrometer-long cracks on the surface. This eventually leads to significant layer tilt in the strain-balanced SL and in the formation of millimeter-long, free-standing flakes. These results confirm the local uniformity of structural properties and highlight the critical importance of threading dislocations in shaping the wafer-level stability of thick multi-quantum well heterostructures required to implement effective silicon-compatible Ge/SiGe photonic devices. [ABSTRACT FROM AUTHOR]

Carbene and its analogous silylene and germylene ligated trinuclear gold complexes are well established due to their cationic stability, but the anionic stability of such complexes is still rare. Density functional theory calculations on recently synthesized [Au3{C4H4(SiMe3)4Si}3]− and [Au3{C4H4(SiMe3)4Ge}3]− prove that the Au3 core is electron rich and the calculated vertical detachment energy is close to that of halogens. Further proper ligand manipulation on these complexes makes them remarkably stable anions having electron binding energies higher than 5 eV and behaving like superhalogens. Magnetic response calculations based on the magnetically induced current densities and the induced magnetic field confirm the aromatic nature of these anionic Au3-complexes. A study of the gradient Laplacian of electron density and energy density at the bond critical point and electron localization function gives additional bonding information of these anionic complexes. [ABSTRACT FROM AUTHOR]

Carbon family elements (Si, Ge, Sn, Pb) have attracted a lot of attention because of their unique structural features and potential applications in microelectronics industry. Here, the structure, chemical stability, electronic properties, and nonlinear optical properties of neutral and charged Au@X20H20 (X=Si, Ge, Sn, Pb) clusters have been systematically studied using density‐functional theory calculations. Structurally, the neutral/anionic Au@X20H20 (X=Si, Ge, Sn) as well as cationic Au@Pb20H20 possess Au‐endohedral (XH)20 unit, forming fullerene‐like framework, whereas other species are Au‐doped structures with hydrogen‐bridged bond. Analysis of binding energy and HOMO‐LUMO energy gaps reveals that the charged clusters possess high chemical stabilities due to closed‐shell structures. The charge transfers from X20 cage to Au atom, and the Au atom acts as electron acceptor. The Au atom and charged states play an important role in the structural stability, and can effectively modulate the electronic properties of clusters. Interestingly, the neutral Au@X20H20 (X=Si, Sn) clusters possess large first hyperpolarizabilities, especially for Au@Sn20H20, which has remarkably giant value (~5.65×108 a. u.), and the enhanced NLO behaviors can be further explained by the TDDFT calculation. The work may provide a theoretical reference for further applications considered as novel cluster‐assembled nanomaterials. [ABSTRACT FROM AUTHOR]

The microstructure, corrosion resistance, and phase-transition process of micro-arc oxidation (MAO) coatings prepared on LaFe11.6Si1.4 alloy surfaces in different electrolyte systems were systematically investigated. Research has demonstrated that various electrolyte systems do not alter the main components of the coatings. However, the synergistic action of Na2CO3 and Na2B4O7 more effectively modulated the ionization and chemical reactions of the MAO process and accelerated the formation of α-Al2O3. Moreover, the addition of Na2CO3 and Na2B4O7 improved the micromorphology of the coating, resulting in a uniform coating thickness and good bonding with the LaFe11.6Si1.4 substrate. The dynamic potential polarization analysis was performed in a three-electrode system consisting of a LaFe11.6Si1.4 working electrode, a saturated calomel reference electrode, and a platinum auxiliary electrode. The results showed that the self-corrosion potential of the LaFe11.6Si1.4 alloy without surface treatment was −0.68 V, with a current density of 8.96 × 10−6 A/cm2. In contrast, the presence of a micro-arc electrolytic oxidation coating significantly improved the corrosion resistance of the LaFe11.6Si1.4 substrate, where the minimum corrosion current density was 1.32 × 10−7 A/cm2 and the corrosion potential was −0.50 V. Similarly, after optimizing the MAO electrolyte with Na2CO3 and Na2B4O7, the corrosion resistance of the material further improved. Simultaneously, the effect of the coatings on the order of the phase transition, latent heat, and temperature is negligible. Therefore, micro-arc oxidation technology based on the in situ growth coating of the material surface effectively improves the working life and stability of La(Fe, Si)13 materials in the refrigeration cycle, which is an excellent alternative as a protection technology to promote the practical process of magnetic refrigeration technology. [ABSTRACT FROM AUTHOR]

High energy‐conversion efficiency (ZT) of thermoelectric materials has been achieved in heavy metal chalcogenides, but the use of toxic Pb or Te is an obstacle for wide applications of thermoelectricity. Here, high ZT is demonstrated in toxic‐element free Ba3BO (B = Si and Ge) with inverse‐perovskite structure. The negatively charged B ion contributes to hole transport with long carrier life time, and their highly dispersive bands with multiple valley degeneracy realize both high p‐type electronic conductivity and high Seebeck coefficient, resulting in high power factor (PF). In addition, extremely low lattice thermal conductivities (κlat) 1.0–0.4 W m−1 K−1 at T = 300–600 K are observed in Ba3BO. Highly distorted O–Ba6 octahedral framework with weak ionic bonds between Ba with large mass and O provides low phonon velocities and strong phonon scattering in Ba3BO. As a consequence of high PF and low κlat, Ba3SiO (Ba3GeO) exhibits rather high ZT = 0.16–0.84 (0.35–0.65) at T = 300–623 K (300–523 K). Finally, based on first‐principles carrier and phonon transport calculations, maximum ZT is predicted to be 2.14 for Ba3SiO and 1.21 for Ba3GeO at T = 600 K by optimizing hole concentration. Present results propose that inverse‐perovskites would be a new platform of environmentally‐benign high‐ZT thermoelectric materials. [ABSTRACT FROM AUTHOR]

The solid waste produced from the germanium extraction process has attached much attention to its potential germanium sources. However, the elemental distribution of solid waste is still unclear. Therefore, the solid waste was studied using a sequential extraction procedure and characterizations including XRD, FTIR, XPS, SEM–EDS, and XAFS. It has been found that Ca, S, Fe, and Si could present crystal occurrence forms such as calcium sulfate, iron oxide hydroxide, or quartz. Furthermore, Si and Al can form a certain amount of amorphous substance. Accordingly, the sequential leaching results tell that Ca and S can be mostly leached out in pure water or weak acid solution, and more than 50% of Fe, Al, and Si were leached out in the reducible or oxidizable environment. Additionally, a part of S could be associated with Pb, generating a mostly Pb-bearing sulfate structure. Most of Zn was leached out from the reducible step, and only a very small part of Zn presented in the residual state, indicating that the majority of Zn might exist in an oxidation state and a small amount of Zn is associated in the amorphous phase. In terms of Ge, As, and Cr, almost all of them existed in the residual state. Ge should be in the occurrence of Si/Al amorphous structure. Similarly, Cr should be most likely to associate with silicates. Furthermore, As is mainly associated with iron mineral through the formation of the binuclear bidentate corner–sharing complex. [ABSTRACT FROM AUTHOR]

Melt treatment is well known to have an important influence on the properties of metallic glasses (MGs). However, for the MGs quenched from different melt temperatures with a quartz tube, the underlying physical origin responsible for the variation of properties remains poorly understood. In the present work, we systematically studied the influence of melt treatment on the thermal properties of a Zr50Cu36Al14 glass-forming alloy and unveiled the microscopic origins. Specifically, we quenched the melt at different temperatures ranging from 1.1 T l to 1.5 T l (T l is the liquidus temperature) to obtain melt-spun MG ribbons and investigated the variation of thermal properties of the MGs upon heating. We found that glass transition temperature, T g, increases by as much as 36 K, and the supercooled liquid region disappears in the curve of differential scanning calorimetry when the melt is quenched at a high temperature up to 1.5 T l. The careful chemical analyses indicate that the change in glass transition behavior originates from the incorporation of oxygen and silicon in the molten alloys. The incorporated oxygen and silicon can both enhance the interactions between atoms, which renders the cooperative rearrangements of atoms difficult, and thus enhances the kinetic stability of the MGs. [ABSTRACT FROM AUTHOR]

Strontium silicates doped with an alkali metal are extensively investigated after their high conductivity reported in the moderate range of temperature (773 K < T < 1073 K). This work aims to study the structural, microstructural, morphological, thermal, and electrical investigation of Sr3-3xNa3xSi3-3yGe3yO9-δ (0 < x < 0.20, y = 0.1; SNSG) system. A solid-state reaction method was adopted for synthesis of the compositions. Composition's phase formation was examined using X-rays Rietveld refinement techniques. X-Ray Diffraction (XRD) patterns were mapped by the monoclinic symmetry having space-group C12/c1. Moreover, along with monoclinic phase a few minor peaks of Sr2SiO4 were also detected along with prominent peaks of parent SrSiO3. To comprehend the surface morphology of the compositions, scanning electron microscopy has been employed. Studies using Fourier transform infrared spectroscopy and Raman spectroscopy have been carried out to investigate the characteristic bands and vibrations modes of the system. Characteristic valence states of constituent elements and stability of the sintered samples in air were confirmed by the X-ray Photoelectron Spectroscopy (XPS) analysis. The electrical behavior of this system was studied by electrochemical impedance spectroscopy (EIS) techniques. Electrical conductivity of the platinum-coated sintered pellet samples was also calculated to check its feasibility as a cost-effective electrolyte for intermediate temperature range. It has also been observed that in Na-doped compositions, a few amorphous phases of Sodium silicate (Na2Si2O5) formed as impurity that may contribute to the total conductivity. [ABSTRACT FROM AUTHOR]

The HelixJet atmospheric plasma‐assisted synthesis can be a new toolbox to realize dedicated nanoparticle architectures such as Janus‐type morphologies. Silicon nanoparticles produced by the decomposition of Silane molecules are directed into an in‐flight annealing stage. The applied high‐temperature supplies a metal vapor rich atmosphere containing Manganese, Chromium, Iron, and Tin outgassing from the used steel tube. The metal atoms alloy into the Silicon nanoparticles and form a self‐assembled 'Si/MnxSiy‐alloy' Janus nanosphere architecture. The Janus particles nanochemistry is thoroughly examined in detail by the analytic capabilities of transmission electron microscopy. The combined approach of electron diffraction, EDS, and EELS identifies the Janus particle composition consisting of a pure Si hemisphere interfaced to an alloyed Mn4Si7 hemisphere covered by a thin (MnaFebCrc)Siy surface shell. [ABSTRACT FROM AUTHOR]

Apatites, being one of the most numerous mineral-like families of compounds, are considered as a matrix for binding lead ions, which is dangerous for the biosphere. The crystal-chemical (composition, structure) and thermophysical aspects (thermal expansion) are considered as the basis for analysing the properties of this kind of material. It is suggested that substances of the composition Pb5(AIVO4)2(BVIO4), Pb5(AIVO4)(CVO4)2 can be a perspective form of lead binding materials based on compounds with the structure of apatite (AIV = Si, Ge; BVI = S, Cr; CV = P). Such compounds, as it was shown by DTA and HTXRD experiments, are distinguished by the absence of polymerphism and the abnormal ordering of structure. Also, they have relatively low values of thermophysical indicators (the rate of change of linear thermal expansion coefficients is 0.02-0.03×106 K-1; values of the volume thermal expansion coefficients are 40-70×106 K-1). Compounds Pb5(SiO4)(PO4)2 (a = 9.78782(16) Å, c = 7.31084(16) Å, V = 606.555(23) Å3, R-bragg = 4.694 %) and Pb5(GeO4)(PO4)2 (a = 9.87697(12) Å, c = 7.33136(11) Å, V = 619.388(17) Å3, R-bragg = 1.730 %) were obtained, identified and crystallographically characterised for the first time. [ABSTRACT FROM AUTHOR]

The atomic-scale structures of Al–Si eutectics and hypereutectic are studied by using global structure searching method combined with ab initio density functional theories. The chemical components Al7Si, Al6Si and Al4Si, with silicon contents of 12.9, 14.7 and 20.6 wt%, are set for searching the lowest-energy structures. The global search results show that all of the low-energy structures demonstrate the fcc structure feature of pure aluminum crystal; while, the alloy structures distort slightly due to the addition of silicon. In the term of binding energy, the stabilities of the alloys enhance with increasing the silicon contents. The binding energies are approximated as the sum of the bond energies, and the least square fitting results give the Al–Al, Al–Si and Si–Si bond energies as − 0.624, − 0.731 and − 0.819 eV, respectively. Forming two Al–Si bonds sacrifices one Si–Si and one Al–Al bonds, and the Al–Si alloys have an energy gain of − 0.019 eV. It suggests that dispersion of silicon atoms in the alloys is favorable for the stability. The mechanical properties of the structures are calculated. While the bulk moduli of the alloys are very close, the shear and Young's moduli are quite different for different structures with different distributions of silicon atoms. [ABSTRACT FROM AUTHOR]

The physicochemical conditions of the siliconizing and boron–siliconizing processes of molybdenum-based alloys in a closed reaction space in an environment of chlorine and fluorine at reduced pressure were studied. Theoretical calculations of the equilibrium composition of systems with the participation of silicon, boron, molybdenum, nitrogen, oxygen, chlorine, and fluorine were carried out, which made it possible to determine the influence of process parameters (temperature, composition of the reaction medium) on the probable phase composition of the obtained coatings. Based on thermodynamic calculations, the composition and rational consumption of the initial powders and the temperature intervals of the chemical heat treatment (CHT) during the complex saturation of molybdenum-based alloys with silicon and boron were modeled. It was established that it is advisable to use chlorine as an activator, which leads to the formation of molybdenum chlorides MoCl4 and MoCl3 in the composition of the gas phase and can indicate the flow of exchange reactions between chlorides and the matrix of the processed material in the reaction space. The rational saturation temperature of alloys based on molybdenum with silicon and boron is determined—1100–1250 °C. The possibility of the existence of condensed phases MoSi2, MoB2.15, B6Si, MoB1.65, and MoB is shown. [ABSTRACT FROM AUTHOR]

Hot dip galvanized products are widely used in various aspects of production and life due to their excellent corrosion resistance. Some studies have added a fourth trace alloying element to the zinc aluminum magnesium coating to form a quaternary alloy for better performance. This article prepared two different types of Zn−Al−Mg alloy ingots with trace amounts of Si added by induction melting, consisting of Zn1Al1Mg0.01Si and Zn1Al1Mg0.05Si, and solidified them in a heating furnace with argon gas protection atmosphere. The precipitation process of Zn1Al1Mg(0.01,0.05)Si alloy components under non equilibrium and equilibrium solidification conditions was calculated. The initial crystalline phase of the alloy and the initial solidification temperature were predicted through phase diagram calculations. The microstructure and phase types of the alloy were analyzed using scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM). The electrochemical Tafel curves of Zn1Al1Mg(0.01,0.05)Si with different Si contents showed that the Zn1Al1Mg0.05Si has the highest corrosion potential and Zn1Al1Mg0.01Si has the lowest corrosion current which means the 1Al1Mg0.01Si alloy possesses the highest corrosion resistance. The Nyqust curves and bode curves also showed that the practical impedance of 1Al1Mg0.01Si alloy is higher than that of 1Al1Mg0.05Si. Moreover, electron probe X-ray micro-analyzer(EPMA) reveals the distribution of Si elements in the Zn1Al1Mg(0.01,0.05)Si. At present, there is little research on the microstructure and properties of quaternary alloys containing silicon. Therefore, studying the influence of silicon content on the microstructure and properties of alloys is of great significance. [ABSTRACT FROM AUTHOR]

Most engineering problems are complicated, and developing mathematical models for such problems requires understanding the phenomena through experiments. It is well known that as processing parameters with assigned levels increase, so does the number of experiments. By minimizing the number of experiments, Taguchi's method of experimental design will help to furnish the idea of full factorial experimental design. Taguchi's method is more appropriate for single-objective optimization problems and needs modifications while dealing with multi-objective optimization problems. Aluminum alloys are in great demand in today's automotive and aerospace sectors due to their low density, good corrosion resistance, and excellent machinability. The material is subjected to a constrained groove pressing (CGP) process to obtain microstructural grain refinement with enhanced mechanical behavior. This paper considers AA6061 material having major alloys such as silicon and magnesium. For this work, 3 CGP process parameters (viz., displacement rate, plate thickness and number of passes) are assigned 3 levels to each parameter, acquired the test data, viz., grain size (gs), micro hardness (hs), and tensile strength (σult) based on L9 orthogonal array of Taguchi. Using a modified version of Taguchi's methodology, it is possible to estimate the range of grain size (gs), micro hardness (hs), and tensile strength (σult) for effective combinations of the CGP processing parameters and validate the results with existing test data. A more dependable and simpler multi-objective optimization procedure is used to choose the optimal CGP processing parameters. [ABSTRACT FROM AUTHOR]

The present research aims to study the effect of Ge concentration on diode parameters of Cu2ZnSn1−xGexS4/CdS solar cells using Ge/Sn ratio in the range of 0–0.25 mol%. A stable molecular ink was formulated to prepare Ge-alloyed Cu2ZnSnS4 (CZTS) thin films and integrated into the superstrate configuration of glass/FTO/TiO2/CdS/CZTGS/graphite heterostructure. Ge incorporation in CZTS lattice was confirmed by XRD analysis and Raman scattering analysis. A detailed inspection of Raman results suggests an increment in Cu–Zn disorder in CZTS films with the increase in Ge. The absorbance measurements revealed that the band gap of Cu2ZnSn1−xGexS4 (CZTGS) was increased systematically from 1.46 to 1.61 eV by increasing the Ge concentration. The dark current–voltage (J–V) characteristics of the heterostructures were analyzed by thermionic emission model using Rhoderick, Cheung–Cheung and Norde methods. By increasing Ge amount, the ideality factor was decreased significantly from 5 to 2.28, while the series resistance was reduced from 980 to 75 Ωcm2. The J–V measurements under illumination indicate that the controlled Ge incorporation in CZTGS/CdS heterostructures improved the photovoltaic parameters such as open circuit voltage, fill factor (FF) and the device efficiency. Stability study of the devices revealed that the Ge incorporated solar cells are more stable than the one without Ge. The present research may provide a promising way for the design of efficient superstrate solar cells or other optoelectronic devices. [ABSTRACT FROM AUTHOR]

Germanate oxides have garnered considerable interest owing to their diverse structural configuration and intriguing properties. Herein, we present a novel niobium germanate crystal, Rb8Nb10Ge6O41, extracted through the process of spontaneous crystallization. It showcases a unique three-dimensional (3D) structural framework composed of one-dimensional (1D) twisted [Nb7O30]∞ chains and isolated [Ge3O9] rings, arising from the divergent polymerized manifestations of [NbO6] and [GeO4] basic building blocks, respectively, marking the first instance of such a topography in germanate materials. Notably, the title compound exhibits exceptional thermal stability up to 1250 °C with a good congruent melting nature. Moreover, it achieves a short ultraviolet edge at 306 nm and a favorable infrared edge cutoff exceeding 6.2 μm, thus indicating a wide transparency window. Additionally, this study elucidates the microscopic birefringence of Rb8Nb10Ge6O41 and clarifies the intricate relationship between its structure and properties. Our findings suggest that the polymerization of distinct structural motifs within a single compound is an effective strategy for exploring novel inorganic materials. [ABSTRACT FROM AUTHOR]

Calcium-magnesium-alumina-silicate (CMAS) resistance has become a key parameter to evaluate the properties of thermal barrier coating (TBC) materials. The CMAS corrosion behavior of BMT ceramic as a novel candidate material for TBC is poorly understood. In this paper, the solid-state sintering process was used to prepare the BMT bulks, and the evolution of microstructure, phase composition, thermophysical properties, and mechanical properties of the BMT bulks exposed to CMAS corrosion were studied. The results indicate that obvious elemental interdiffusion between the CMAS melt and BMT occurred at 1250 °C, which changed the original phase composition and formed multiple substances including Ba(Al, Ca)Si 2 O 8 , Ba 2 MgSi 2 O 7 , BaTa 2 O 6 , Ba 2 Si 4 O 10 , etc. The microstructure of BMT also underwent changes due to differences in the diffusion coefficients of different elements. As corrosion time prolongs, an obvious porous columnar reaction layer formed on the sample surface, causing the CMAS melt to sustainably corrode the deep BMT, resulting in intragranular corrosion. In terms of properties, the thermophysical and mechanical properties of the BMT bulks corroded by CMAS deteriorated. The thermal conductivity at 1100 °C increased from 1.43 W m−1 · k−1 to 1.67 W m−1 · k−1. The average coefficient of thermal expansion at 200–1400 °C decreased from 11.60 × 10−6 K−1 to 10.95 × 10−6 K−1. The hardness dropped by 21 % compared to the original BMT bulk. Therefore, it is necessary to improve the CMAS resistance of BMT ceramic in future studies. [ABSTRACT FROM AUTHOR]

The work is devoted to the study of the effect of multi-step heat treatment on the formation of the microstructure of the alloy of Al–Mg–Si series, alloyed with scandium and zirconium at the ratio of Mg/Si = 0.3. For this purpose, the base AlMgSi alloy, containing no scandium and zirconium, as well as its modification AlMgSiScZr with additions of these elements were cast. Multi-step heat treatment of AlMgSiScZr alloy consisted of four steps of annealing: at 550°C for 8 h + at 440°C for 8 h + at 500°C for 0.5 h + at 180°C for 5 h. For AlMgSi alloy, it included two steps: at 550°C for 8 h + at 180°C for 5 h. The microstructure of AlMgSiScZr alloy was studied in the cast state, as well as after each step of heat treatment by scanning and transmission electron microscopy, while AlMgSi alloy was studied in the cast state and after the final heat treatment. After each step of heat treatment, the microhardness of the studied alloys was measured. It was found that during cooling of the ingot, in the alloys under consideration coarse intermetallics of Fe2Mg7Si10Al18 type were formed, which partially were dissolved during subsequent heat treatment. At the same time, in the alloy with scandium and zirconium additives, particles that can be attributed either to (AlSi)3ScZr or to the τ (phase) of AlSc2Si2 are present at the intergranular boundaries. No traces of intermittent decomposition of the scandium supersaturated solid solution during cooling of the ingot were found. Heat treatment at 550°C for 8 h + at 440°C for 8 h leads to the appearance of a phase that can be both AlSc2Si2 and Al5SiZr2, while no (AlSi)3ScZr nanoparticles are formed. Heating at 500°C for 30 min enables complete dissolution of the magnesium-containing particles. At the final step, β" (Mg5Si6) particles are formed in the investigated alloys, while scandium has no significant effect on their formation. [ABSTRACT FROM AUTHOR]

Wide band gaps and large second harmonic generation (SHG) response are two crucial yet contradictory parameters for nonlinear optical (NLO) crystals. Herein, through exploring the influence of anion groups on structural crystallization dimension and space group, a series of new NLO Hg‐based chalcogenides AIIHgMIVS4 (AII = Sr, Ba, MIV = Si, Ge) with wide band gaps and large SHG responses have been successfully designed and synthesized. The structures of these compounds consist of 2D [HgMS4]2− (M = Si and Ge) layers composed of distorted (HgS4 and MS4) tetrahedra arranged alternately, and the layers are separated by eight‐coordinated A2+ (A = Sr and Ba) cations. Their band gaps and SHG responses meet the basic requirements (SHG > 1 × AgGaS2; Eg > 2.33 eV). Especially, SrHgSiS4 and SrHgGeS4 exhibit both large SHG effects (2 and 2.4 × AgGaS2) and wide band gaps (3.06 and 2.97 eV), respectively, indicating they are promising IR NLO crystals. This work opens a new avenue for new NLO material design to achieve the balance between strong SHG response and large band gaps. [ABSTRACT FROM AUTHOR]

The chromium (Cr) evaporation from balance-of-plant (BoP) component alloys in high-temperature environments can severely deteriorate the electrochemical performance of solid oxide cells (SOCs) in fuel (SOFC) and electrolysis (SOEC) modes. However, accurate assessment of Cr evaporation is challenging due to potential interferences from the experimental conditions and test apparatus. In this study, we investigate four distinct methods for assessing the Cr evaporation rates of candidate alumina-forming austenitic and chromia-forming austenitic BoP alloys under relevant simulated SOC operating conditions of 800–900 °C in air with 10% H2O. A method using a sodium carbonate coated thin alumina tube is identified, which effectively mitigates the interference caused by (1) the deposition of silicon deposits originating from quartz furnace tubes, (2) detrimental effects of sodium species on the oxidation process of alloys from the sodium carbonate used to enhance Cr oxy hydroxide species capture, or (3) chemical interaction between Cr gaseous species and the alumina furnace tube. This optimal method provides improved assessment of Cr evaporation, enabling further efforts to build correlation between Cr species quantities to the degradation rates of SOCs. [ABSTRACT FROM AUTHOR]

Theoretical evaluation of gallium nano-clusters decorated with certain metalloids (B, Si and Ge) ( Ga 1 2 X 1 2 , where X = N, O) as proficient adsorbents for 2,4-dichloropropionic acid (Dal) was conducted using the DFT/ ω B97X-D functional with a 6-311++G(d,p) basis set. Notably, the Ga 1 2 O 1 2 -decorated nano-structures demonstrated superior efficiency compared to their Ga 1 2 N 1 2 counterparts. In the analysis of electronic structure, Ga@Si_Dal (GS2) exhibited a narrow band gap of 3.237 eV between the conduction and valence bands, signifying heightened system conductivity. For the adsorption system, Ga@Si_Dal (GS2) displayed an adsorption distance of 2.45400 Å, with the most stable optimal value of −2159.31 upon Dal adsorption. GaN@B_Dal (B1) exhibited the shortest bond length at 1.267 Å. The computed adsorption energy values for comparative assessment were universally negative, indicating robust interaction between adsorbent and adsorbate. GaO@Ge_Dal (GG2) boasted the most negative adsorption energy at −4.811 kcal/mol when compared with other decorated surfaces. The study underscored GaO@Si_Dal (GS2) as possessing a more potent non-covalent interaction than other adorned surfaces, as substantiated by its higher electron density and Laplacian of electron density. This research offers valuable insights for both researchers and industrialists engaged in combating environmental pollution. Theoretical evaluation of gallium nano-clusters decorated with certain metalloids (B, Si, and Ge) ( Ga 1 2 X 1 2 , where X = N, O) as proficient adsorbents for 2,4-dichloropropionic acid (Dal) was conducted using the DFT/ ω B97X-D functional with a 6-311++G(d,p) basis set. [ABSTRACT FROM AUTHOR]

We perform a photoluminescence comparison of Ge nanocrystals in an Al2O3 matrix structures with similar Ge-Si core–shell nanoparticles structures. Al2O3/Ge and Al2O3/Si/Ge/Si nanoperiodic structures were obtained by electron beam evaporation with subsequent high-temperature (800–900 °C) annealing in an inert medium. The first type of structure has an intensive visible luminescence, which may be associated with a large number of structural defects. Al2O3/Si/Ge/Si structures have a very weak photoluminescence in the visible spectral region and an additional maximum in the 800–1000 nm. The last one is caused mostly by Ge/SiGe nanocrystals. Further work to enhance this infrared emission by increasing the layer thickness, testing annealing modes, duration, and annealing atmosphere opens up prospects for the use of such structures in light-emitting devices. [ABSTRACT FROM AUTHOR]

Hydrogen embrittlement (HE) of 1.4614 and 1.4543 maraging stainless steels is characterized with fine structural TEM-ASTAR, hydrogen electrochemical permeation, thermodesorption and tensile testing (with slow strain rate during H cathodic charging) experiments. Both solutions annealed and 550 °C aged states are studied. When aged, 1.4614 grade contains nanometric hexagonal Ni3Ti precipitates whereas 1.4543 grade contains three families of nanometric precipitates, namely, hexagonal Ni3Ti, non fcc-rich Cu and G-phase rich in Si, Ti and Ni with cube-cube relations with martensite. From the permeation and thermodesorption results, it appears that austenite and nanometric precipitates seem to constitute deep traps for hydrogen in both grades. From tensile tests with in situ H charging, 1.4614 and 1.4543 maraging grades show a high susceptibility to HE with relative reduction of area (RRA) strictly superior to 80% for both metallurgical states. The presence of retained austenite does not seem to bring any HE resistance because of its transformation into martensite during deformation. [ABSTRACT FROM AUTHOR]

Cast Monel alloys are used in many industrial applications that require a combination of good mechanical properties and excellent resistance to corrosion. Despite relative widespread use, there has been limited prior research investigating the fundamental composition–structure–property relationships. In this work, microstructural characterization, thermal analysis, electron probe microanalysis, tensile testing, and Varestraint testing were used to assess the effects of variations in nominal composition on the solidification path, microstructure, mechanical properties, and solidification cracking susceptibility of cast Monel alloys. It was found that Si segregation caused the formation of silicides at the end of solidification in grades containing at least 3 wt pct Si. While increases to Si content led to significant improvements in strengthening due to the precipitation of β1-Ni3Si, the silicide eutectics acted as crack nucleation sites during tensile loading which severely reduced ductility. The solidification cracking susceptibility of low-Si Monel alloys was found to be relatively low. However, increases to Si concentration and the onset of associated eutectic reactions increased the solidification temperature range and drastically reduced cracking resistance. Increases in the Cu and Mn concentrations were found to reduce the solubility limit of Si in austenite which promoted additional eutectic formation and exacerbated the reductions in ductility and/or weldability. [ABSTRACT FROM AUTHOR]

The evolution of eutectic Si morphology and microsegregation during homogenization heat treatment at 753K was examined for Al--Si--Cu--Mg--Ni alloy casting billets. Subsequently, casting billets homogenized at 753K for 0 s, 7.2 ks, and 28.8 ks were forged, and microstructures and mechanical properties at 473 and 573K were investigated for the forgings with different sizes of eutectic Si. Spheroidization of eutectic Si and elimination of microsegregation were achieved during the heating process of homogenization heat treatment. The spheroidized eutectic Si then coarsened with the homogenization heat treatment time. The interparticle spacing of the eutectic Si and constituent particles after the forging process increased with the coarsening of Si particles during homogenization heat treatment. In the tensile test at 473 K, the 0.2% proof stress, ultimate tensile strength (UTS), and elongation of the forgings were almost the same regardless of the homogenization heat treatment time, i.e., the size of eutectic Si. On the other hand, forgings made of a billet with a shorter homogenization heat treatment time showed more pronounced work-hardening behavior and higher 0.2% proof stress and UTS at 573 K. The increase in strength was explained by the enhancement of workhardening associated with the decrease in interparticle spacing, which depends on the Si particle size after homogenization heat treatment. [ABSTRACT FROM AUTHOR]

Cast Al-Si alloys, recognized for their excellent mechanical properties, constitute one of the most widely employed non-ferrous substrates in several sectors, and are particularly relevant in the transport industry. Nevertheless, these alloys also display inherent limitations that significantly restrict their use in several applications. Among these limitations, their low hardness, low wear resistance, or limited anti-corrosion properties, which are often not enough when the component is subjected to more severe environments, are particularly relevant. In this context, surface modification and the development of coatings are essential for the application of cast Al-Si alloys. This review focuses on the development of coatings to overcome the complexities associated with improving the performance of cast Al-Si alloys. Against this background, plasma electrolytic oxidation (PEO), an advanced electrochemical treatment that has revolutionized the surface modification of several metallic alloys in recent years, emerges as a promising approach. Despite the growing recognition of PEO technology, the achievement of high-performance coatings on cast Al-Si is still a challenge nowadays, for which reason this review aims to provide an overview of the PEO treatment applied to these alloys. In particular, the impact of the electrolyte chemical composition on the properties of the coatings obtained on different alloys exposed to harsh environments has been analyzed and discussed. By addressing the existing gaps and challenges, this paper contributes to a better understanding of the intricacies associated with the development of robust PEO coatings on cast Al-Si alloys. [ABSTRACT FROM AUTHOR]

This paper focuses on studying and simulating a GaAs1-xPx/Si1-yGey/Ge triple-junction solar cell structure. First, the strain and the bandgap energy associated to the SiGe layer have been studied. The optimal germanium concentration is 0.88 with a strain around 0.45%. Then, the phosphor concentration effect on the strain and the bandgap energy of the upper layer GaAs1-xPx/Si0.12Ge0.88 has been optimized. At room temperature, the optimal output parameter reach Jsc=34.41mA/cm², Voc=1.27V, FF=88.42% and =38.45% for an absorber thickness of 4.5µm and x=0.47, with a strain that doesn't exceed 1.5%. This study has enabled us to design a high-efficiency, low cost 3J solar cell. [ABSTRACT FROM AUTHOR]

Context: The Pseudo Jahn- Teller effect is a significant tool for evaluating molecular distortion and symmetry breaking. The PJT effect associated with NBO analysis can be a powerful method for studying the structural properties variations arising from D2h → C2h distortions. The theoretical studies on Si2X4+ and Ge2X4+ radical cations have been rare. The calculations have shown that C2h non-planar structures are more stable than planar structures with D2h symmetry. The (B 3 u + B 1 u) ⊗ b 2 g PJTE problem of M2X4+ compounds is a result of the coupling between the ground B3u state and the exited B1u state in the Qb2g direction causes. Also, the difference in M and X atoms can affect the PJT instability of compounds. The findings of this work show that the energy gap between the ground and excited states that have D2h symmetry decreases from M2Cl4+ to M2I4+ and increases from Si2X4+ to Ge2X4+. In fact, there is a significant relationship between instability of high-symmetry configurations, geometric parameters, electron delocalization, chemical hardness, electronegativity, electrophilicity index, and PJT stabilization energies. These results may serve to evaluate the distortion of similar systems. Methods: The structures of Si2X4+ and Ge2X4+ are optimized by LC˗BLYP, M06˗2X, and B3LYP methods with def2˗TZVPP basis set in GAMESS software. The details of the excited states of compounds are studied by the TD-DFT method. NBO analysis for planar and non˗planar structures is carried out at B3LYP/def2˗TZVPP level by the NBO 5. G program that demonstrates HOMO, LUMO, ED, bonding and antibonding orbital occupancies, bond order, and E2. [ABSTRACT FROM AUTHOR]

The article presents the results of thermodynamic prediction and electric smelting of Shalkiya sulfide zinc-lead-bearing ore in the presence of magnetite and coke. Using the HSC-6.0 software package, it was found that under equilibrium conditions in the presence of Fe3O4 and carbon, the reduction and formation of gaseous zinc from ZnS (according to ΔG° = 0) occurs at a temperature of 1205.7 °C, and the formation of ferroalloy at the interaction of the sulfide ore with magnetite and carbon begins at 1200 °C. About 58% of silicon is extracted into the ferroalloy at 1800-1900 ℃; almost all zinc and 83-88% of lead turns into a gaseous state. Electric smelting of the sulfide ore in the presence of magnetite concentrate and coke makes it possible to obtain the FS45 grade ferrosilicon (42-43% of Si); the silicon extraction degree was 84-88%. At the same time, 97.3% of lead and 99.2% of zinc are extracted into the sublimates. The developed method for processing zinc sulfide ores allows us to increase the degree of raw materials' comprehensive use due to the extraction of not only zinc and lead, but also silicon. The technology can be used to process raw materials containing zinc, lead and silica, such as zinc ore concentration tailings. [ABSTRACT FROM AUTHOR]

Increasing the serviceability of industrial components intended for the petrochemical industry is possible through their superficial saturation with silicon (silicon cementation). Obtaining a silicon-rich surface coating results in a considerable increase in corrosion resistance, refractoriness, and wear resistance. One of the most economically convenient options for silicon cementation is pack siliconizing in powdery solid media. This paper presents the possibility of pack siliconizing that contains ferrosilicon (FeSi75C) and a thermite mixture (SiO2 + Al) as active, silicon-providing components, in P265GH grade steel, which is frequently used in the petrochemical industry. The aim of the study was to determine the most suitable active component of the two that were analyzed and at the same time identify the processing conditions in which the siliconized coating has the greatest thickness, is free of porosity, and is in direct contact with the support. The use of experimental programming methods allowed the optimization of the operation to obtain the optimal solution. It was concluded that the thermite mixture is not compatible with pack siliconizing because it results in a superficial saturation predominantly composed of aluminum. When ferrosilicon is used as the active component, it determines the particularly intense formation kinetics of the non-porous siliconized coating with its maximum thickness being reached at high processing temperature values (over 1100 °C) with a proportion of 60% FeSi75 and, simultaneously, with the lowest possible proportion of ammonium chloride (max. 3%), which is the surface activation/cleaning component. [ABSTRACT FROM AUTHOR]

Efficiently passivating germanium (Ge) surfaces is crucial to reduce the unwanted recombination current in high-performance devices. Chemical surface cleaning is critical to remove surface contaminants and Ge oxides, ensuring effective surface passivation after dielectric deposition. However, Ge oxides can rapidly regrow upon air exposure. To understand the surface evolution after wet cleaning, we present a comprehensive study comparing HF and HCl deoxidation steps on p-type Ge surfaces and monitor the surface as a function of air exposure time. Distinct oxide regrowth dynamics are observed: HF-treated samples exhibit swift regrowth of all Ge oxide states, whereas HCl-treated Ge surfaces exhibit a lower concentration of low degrees of oxidation and slower or no regrowth of high oxide states even after 110 min of air exposure. In addition, the presence of Ge–Cl bonds induces different oxidation dynamics compared to the Ge–OH bonds resulting from HF cleaning. This leads to varying surface electronic band structures, with HF-treated Ge exhibiting a strong positive band bending (+ 0.20 eV). Conversely, HCl-treated samples display a lower band curvature (+ 0.07 eV), mostly due to the presence of Ge–Cl bonds on the Ge surface. During air exposure, the increased GeO x coverage significantly reduces the band bending after HF, while a constant band bending is observed after HCl. Finally, these factors induce a reduction in the surface recombination velocity after wet etching. Combining both chemical and field-induced passivation, HF-treated Ge without rinsing exceeds 800 μ s. [ABSTRACT FROM AUTHOR]