Space Group Fm3m Research Articles

Advantageous occupation of Cu2+ in the B site of double-perovskite Rb2BB'Br6 (B = K; B′ = Bi) framework for white-light-emission

Research on lead-free double perovskite has demonstrated its potential as a solution to the stability and toxicity issues associated with lead-based inorganic perovskite white light-emitting diodes (WLED). This current investigation was designed to fabricate, examine, and compare the photoluminescence (PL) characteristics of Cu2+-activated Rb2BB'Br6 (B = K and B′ = Bi) double-perovskite (DP) [A2BB'Br6] luminous materials. Bi3+ ions are substituted with Cu2+ ions at their B′ sites. These ions are distributed to the equilibrium valence state and demonstrate minimal variation in ion radius. The microstructure and phase purity of Rb2BB'Br6:Cu2+ DP were assessed by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The Rietveld refinement was also used to identify the crystal structures, and the resulting samples all exhibit cubic crystal structures. The Fm3m space group in Rb2BB'Br6 DP frameworks is significantly impacted by the B sites. The PL spectra were used to thoroughly examine the associated mechanism of the Cu2+ → Bi3+ energy-transfer process. Cu2+ ions can be successfully doped in the Rb2KBiBr6 host with an optical band gap (Eg) of 2.74 eV (RKBBr: 0.025Cu2+). The Rb2KBiBr6:Cu2+ phosphor exhibits distinct emission bands from 450 to 650 nm upon UV excitation at 366 nm. The Cu2+→ Bi3+ energy transfer design allows for systematic luminescence tuning from blue to white due to spectral overlap between the Cu2+ emission and Bi3+ excitation spectra. It has been established that Cu2+ → Bi3+ energy transfer significantly increases the white emission intensity of Bi3+, with an associated colour temperature of 7892 K and an outstanding colour rendering index of 88.8. As a down-conversion luminous material in solid-state illumination for the upcoming generation of display devices, the discovered Rb2KBiBr6: 0.025Cu2+ phosphor exhibits remarkable promise.

Structural characterization and dielectric behavior of substituted bismuth niobate Bi17Nb3-4xV2xP2xO33 with fluorite-like structure

Structural, morphological, and dielectric properties of substituted bismuth niobates Bi17Nb3-4xV2xP2xO33 with a fluorite-like structure have been reported. The study focuses on substituting Nb5+ with V5+ and P5+ cations in Bi17Nb3O33. The resulting ceramics were synthesized using the solid-state reaction technique, and their crystal structure was analyzed using X-ray diffraction. The analysis confirmed the stabilization of the compounds in a single phase of a cubic fluorite structure. Structural refinement analysis has been performed for the compound Bi17Nb2.4V0.3P0.3O33 to investigate the details of the crystalline structure which was found to be a cubic fluorite structure at room temperature (space group Fm3‾m). Scanning Electron Microscopy (SEM) was used to examine the surface morphology of the samples, which exhibited irregular shapes and heterogeneous size distribution. The dielectric properties of the ceramics were analyzed, and the dielectric permittivity (ε’) and loss factor (tan δ) were measured at different frequencies and temperatures. The results showed anomalies in each frequency-dependent curve, indicating a relaxation phenomenon. The electrical conductivity (σ) of the ceramics was studied, and it was found that the conductivity displayed a frequency-independent plateau at low frequencies, indicating a semiconductor behavior. The complex impedance spectra and electrical modulus analysis were also conducted to investigate the relaxation processes in the material.

Batch studies on uranium uptake by CeO2 nanoparticles from its aqueous solution

Uranium is a radioactive heavy metal, whose presence in groundwater is harmful to human health and the environment. Thus, the special attentionisfocused on technologiesthat separateuranium from different water sources. CeO2 were synthesized by employing a solution combustion process to remove U (VI) ions from an aqueous medium. The material characterisation revealed face-centred cubic phase of CeO2 with a space group of Fm3m, with porous shape of surface area 65.581 m2/g and 7.28 nm of pore diameter. Optimised batch experiments were carried out by varyingthe contact time(0–90 min), pH of thesolution(2–9), and concentration of U (VI)from 100 to 500 µg/L at room temperature. The maximum removal of U (VI) ions under the specified conditions was found to be significant using CeO2 (≥90 %). Maximum U (VI) adsorption was observed at contact time of 70 min, pH between 6 and 7 with 100 µg/L of U (VI) aqueous solution for a 0.01 g/L of nanoadsorbent dosage. The Langmuir isotherm, with a maximum adsorption capacity of 1294.02 μg/g, was found to best fit the adsorption process. As per the kinetic studies, it illustrated that the adsorption process followed a pseudo-second-order model with an adsorption capacity of 1000 μg/g.

Fabrication of Highly Sensitive YCeO Chemo-resistive Gas Sensor for Selective Detection of CO2

A room-temperature-operated CO2 gas sensor based on YCeO nanocomposite was effectively prepared by the simple hydrothermal technique to detect low traces of CO2 (50–250 ppm). The YCeO granular morphological features were observed using field-emission scanning electron microscopy, which confirmed successful fabrication of nanocomposite of Y2O3 and CeO2. X-ray diffraction of YCeO showed the Cubic structure of space group Fm3m having density 6.74 gmcm−3. Rietveld refinement was performed for the analysis of complete crystal structural property. Surface porosity and specific surface area were observed by Brunnauer-Emmet Teller analysis. Optical properties were observed using UV-Visible spectroscopy. The band gap, optical conductivity, and refractive index calculated were 3.44 eV, 2.63 × 106, and 0.1164, respectively. Fourier transform infrared spectroscopy was done to analyze the functional and elastic properties of as-prepared nanomaterial. The highest sensor response recorded was 2.14. The response and recovery time at 50 ppm observed were 75.6 and 107.3 s, respectively. The YCeO chemo-resistive sensor confirmed long-term stability and selectivity to CO2 as compared to other gases viz. LPG, NH3, CH4, H2S, NO2 and H2. The relative humidity exposure was also performed at 15, 55 and 95% RH, in which it was confirmed that the sensor would give best response at mid humidity level i.e. 55 %RH. Sensing characteristics curve of YCeO nanocomposite at different temperature (30 °C–90 °C) at 50 ppm confirmed that YCeO sensor performed excellent at room temperature. This report unlocks an innovative opening for the fabrication of sensing devices that are room-temperature-operatable, highly sensitive and selective for quick detection of CO2 gas for its commercialization.

The ultralow loss Li2Mg3Ti1−xAl4x/3O6 microwave dielectric ceramics and its design of dielectric resonator antenna

The Li2Mg3Ti1−xAl4x/3O6 (0 ≤ x ≤ 0.1) ceramics are synthesized using the solid phase method, showing excellent microwave dielectric properties with εr = 14.05, Q × f = 144 500 GHz, and τf = −43 ppm/°C at x = 0.04. Rietveld refinements, based on the XRD data, reveal that the Li2Mg3Ti1−xAl4x/3O6 ceramics crystallize in the rock salt structure with Fm-3m space group. The relationship between the crystal structure and intrinsic microwave dielectric properties is studied in detail. The variation in the dielectric constant is related to ionic polarization and relative density. The quality factor (Q × f) demonstrates a strong correlation with lattice energy, relative density, and concentration of Ti3+. The variation of τf is influenced by the bond thermal expansion coefficient and bond valence. The dielectric resonant antenna, manufactured from Li2Mg3Ti0.96Al0.0533O6-0.09TiO2 ceramic with near-zero τf, shows a bandwidth of 230 MHz at 7.40 GHz and a high radiant efficiency, which indicates that high-quality factor Li2Mg3Ti0.96Al0.0533O6 ceramic has significant potential in relevant fields such as 5G and smart driving.

Band gap engineering through calcium addition in (Mg, Co, Ni, Cu, Zn)O high entropy oxide for efficient photocatalysis

Multicomponent metal oxides have shown the potential to be excellent catalysts mainly because of synergistic interactions between the active sites. We report (Co, Mg, Ni, Cu, Zn)1-xCaxO (x = 0.05, 0.1) high entropy oxide (HEO) photocatalyst with single phase rocksalt structure (space group Fm3¯m) synthesized by solution combustion synthesis (SCS) technique. HEOs contain elements with varying electronegativities and crystal field splitting and thus exhibit a relatively lower band gap when compared to the individual constituent oxides. Adding Ca2+ results in increased covalency due to the greater exchange interaction between O 2p and transition metal (TM) 3d orbital, engendering further reduction in band gap and consequently improving photocatalytic activity in the visible region. In addition, the introduction of point defects, mainly metal/oxygen vacancy, to accommodate the larger size Ca2+ cation also contributed to the catalytic activity. The photocatalytic activity enhancement is demonstrated by visible light-assisted photodegradation of methylene blue (MB). The MB dye degradation rate constant for (Co, Ni, Cu, Zn, Mg)0.9Ca0.1O catalyst was found to be ∼0.0445 min−1, which was about six times faster than that of the pristine (Co, Mg, Ni, Cu, Zn)O.

Ab-initio calculations of structural, vibrational, electronic and elastic properties of fluorite minerals: A computer simulation approach

There are numerous industrial and technological uses for minerals from the fluorite group. Fluorite group minerals, according to Dana's mineralogy, are simple metallic fluorides with a cubic crystal structure that belongs to the space group Fm-3m (225). Fluorite, Stronitiofluorite, Frankdicksonite, and Fluorocronite are the members of fluorite group minerals. These are F-centered cubic minerals, also known as halides, having general formula MF2, where M = Ca, Sr, Ba, and Pb. These minerals have cubic (Fm-3m), orthorhombic (Pnma), and hexagonal (P63/mmc) phases at different pressure. In the present study, the structural optimization of CaF2, SrF2, BaF2, and PbF2 with cubic (Fm-3m) phase has been performed by Density Functional Theory (DFT) calculation using Generalized Gradient Approximation (GGA) with Quantum Espresso code. The electronic band structure of fluorite group minerals has been investigated. From the electronic band structure, it has been found that these minerals are insulator having indirect band gap. Phonon dispersion curves for CaF2, SrF2, BaF2, and PbF2 confirms that fluorite minerals in cubic phase are mechanically stable. LO–TO splitting in the phonon dispersion curves indicates that these mineral have ionic bonding. Also, lattice parameter, elastic constants, bulk modulus, Young's modulus, shear modulus, Poisson's ratio, Pugh's ratio and Cauchy pressure for fluorite minerals have been calculated using Voigt–Reuss–Hill approximation, and the results have been analyzed with experimental data.

Ta/Nb doping motivating cubic phase stability and CO2 tolerance of Sr2Co1.6Fe0.4O6-δ double perovskite for high-performing SOFC cathode

Developing cathodes that are both phase-stable and tolerant to carbon dioxide (CO2) is a crucial and challenging task for solid-oxide fuel cells (SOFCs) operating at reduced temperatures. The activity of oxygen reduction reaction (ORR) in SOFC cathodes is typically influenced by factors such as geometric features and oxygen vacancies. In this study, new and robust cathodes for SOFCs, Sr2Co1.5Fe0.4Ta0.1O5+δ (SCFT) and Sr2Co1.5Fe0.4Nb0.1O5+δ (SCFN) are developed by doping a small amount of niobium (Nb) and tantalum (Ta) into Sr2Co1.6Fe0.4O5+δ (SCF) using a simple solid-state reaction technique. The effects of Nb/Ta doping on the crystal structure, oxygen vacancies, electrical conductivity, and electrochemical properties of SCFT and SCFN are investigated. The results reveal that these materials possess a fully cubic structure in the Fm-3m space group, with improved oxygen vacancy and electrical conductivity. They also exhibit good chemical compatibility with electrolytes at 1100 °C for 8 h and remain thermally stable when exposed to air and CO2 at 700 °C, without any additional phase formation. The area-specific resistance (ASR) of the SCFT cathode is found to be only 0.06 Ω cm2, whereas the SCFN cathode has an ASR of 0.10 Ω cm2. The superior performance of SCFT can be attributed to the higher oxygen vacancy, which enhances oxygen surface exchange kinetics and diffusivity compared to SCFN. When tested in a single cell using humidified H2 as the fuel and ambient air as the oxidant, the SCFT cathode achieves a power density of 656 mW cm−2 at 700 °C, while the SCFN cathode reaches 559 mW cm−2, indicating the potential of SCFT as a promising cathode material for SOFCs. The excellent performance of these materials can be attributed to their mixed electronic-ionic conduction properties, unique structural features, and high observed oxygen vacancy, which contribute to their remarkable electronic conductivity and significant ionic mobility.

Manipulating the Curie point in γ-Fe filled carbon nano-onions: The role of Mn and Gd for enhanced magnetic functionalities

Recent works have proposed the stabilization of γ-Fe nanocrystals inside carbon nano-onions (CNOs) and nanotubes (CNTs) as active ferromagnetic phases for possible applications in hyperthermic dissipative systems. Stabilization of the γ-phase of iron is of particular interest due to the unit-cell dependent ferromagnetic properties and controllable Curie point. Here we investigate a modification of the chemical vapor synthesis (CVS) method for the in-situ manipulation of γ-Fe nanocrystals within CNOs, in presence of bis(isopropyl-cyclopentadienyl)manganese or tris(tetramethyl-cyclopentadienyl)gadolinium(III) as additional growth-precursors. In the presented experiments ferrocene, dichlorobenzene and sulfur mixtures were employed with a fixed ratio. Interestingly, when employing bis(isopropyl-cyclopentadienyl)manganese we demonstrate the stabilization of a modified FCC γ-Fe phase inside the CNOs, identifiable as a γ-Fe23C6 through X-ray diffraction and refinement of the structural model (obtained by employing the Rietveld method), with unit cell parameters a=b=c= 10.5569 Å and space group Fm-3m. The relative amount of Mn content was found to vary from 0.2% to 0.5%. Differently, comparative experiments performed in presence of great excess of tris(tetramethylcyclo-pentadienyl)gadolinium(III) reveal a significant variation of the sample’s morphology, with the nucleation of Gd nanoparticles around γ-Fe filled CNOs. Magnetic characterization with field-dependent zero field cooled (ZFC) and field cooled (FC) acquisitions revealed for the first batch of experiments (method 1) a ferromagnetic behavior comparable to that of γ-Fe, with a T1 Curie point located in proximity of T∼ 400 K and a T2 Curie point in proximity of T∼90 K. Differently, for method-2, an important interplay of ferromagnetic and paramagnetic components was found in the Gd-decorated γ-Fe filled CNOs, with a reduction of the Curie point down to T∼350 K. The presented findings highlight the important role of 1) the γ-Fe23C6 phase in enhancing the saturation magnetization Ms of the filled CNOs and 2) the crystallinity of the Gd-component in allowing for an enhancement of the paramagnetic response in the filled CNOs.

Solution-processable mixed-anion cluster chalcohalide Rb6Re6S8I8 in a light-emitting diode.

Rhenium chalcohalide cluster compounds are a photoluminescent family of mixed-anion chalcohalide cluster materials. Here we report the new material Rb6Re6S8I8, which crystallizes in the cubic space group Fm[Formula: see text]m and contains isolated [Re6S8I6]4- clusters. Rb6Re6S8I8 has a band gap of 2.06(5) eV and an ionization energy of 5.51(3) eV, and exhibits broad photoluminescence (PL) ranging from 1.01 eV to 2.12 eV. The room-temperature PL exhibits a PL quantum yield of 42.7% and a PL lifetime of 77 μs (99 μs at 77 K). Rb6Re6S8I8 is found to be soluble in multiple polar solvents including N,N-dimethylformamide, which enables solution processing of the material into films with thickness under 150 nm. Light-emitting diodes based on films of Rb6Re6S8I8 were fabricated, demonstrating the potential for this family of materials in optoelectronic devices.

Theoretical study of the structural and thermodynamic properties of U-He compounds under high pressure.

Uranium is considered as a very important nuclear energy material because of the huge amount of energy it releases. As the main product of the spontaneous decay of uranium, it is difficult for helium to react with uranium because of its chemical inertness. Therefore, bubbles will be formed inside uranium, which could greatly reduce the performance of uranium or cause safety problems. Additionally, nuclear materials are usually operated in an environment of high-temperature and high-pressure, so it is necessary to figure out the exact state of helium inside uranium under extreme conditions. Here, we explored the structural stability of the U-He system under high pressure and high temperature by using density functional theory calculations. Two metastable phases are found between 50 and 400 GPa: U4He with space group Fmmm and U6He with space group P1̄. Both are metallic and adopt layered structures. Electron localization function calculation combined with charge density difference analysis indicates that there are covalent bonds between U and U atoms in both Fmmm-U4He and P1̄-U6He. Regarding the elastic modulus of α-U, the addition of helium has certain influence on the mechanical properties of uranium. Besides, first-principles molecular dynamics simulations were carried out to study the dynamical behavior of Fmmm-U4He and P1̄-U6He at high-temperature. It was found that Fmmm-U4He and P1̄-U6He undergo one-dimensional superionic phase transitions at 150 GPa. Our study revealed the exotic structure of U-He compounds beyond the formation of bubbles under high-pressure and high-temperature, which might be relevant to the performance and safety issues of nuclear materials under extreme conditions.

Influence of annealing temperature on microstructure and phase transformations of oxide system Bi2O3/TiO2 formed in aqueous solutions

Bismuth titanate is widely used in various fields of science and technology due to its unique physical and chemical properties. Nanostructured metal oxide compounds of the Bi–Ti–O system, consisting of columnar TiO2 nanostructures obtained by electrochemical anodization of a two-layer Ti/Al composition, and platelet Bi2O3 nanostructures formed by sequential ion-layer deposition were synthesized. Morphological changes and phase transformations in the microstructure of the Bi2O3/TiO2 oxide system, which occur during its thermal annealing at temperatures of 150, 300, 500, and 700 °C, have been studied. Annealing of the oxide system in the range of 150–300 °C degrees leads to inconsequential morphological and structural changes: the mixture of oxides is densified, in addition to anatase, a rutile phase appears in TiO2. The crystal system of the Bi2O3 phase is hexagonal. After annealing at 500 °C, not only morphological changes occurred in the studied composite, but also significant transformations in the microstructure. In the film volume, oxide phases Ti2O3 and Bi2O3 began to transform into three-component compound Bi4Ti3O12, and this process is completed at 700 degrees with the formation of single-phase Bi4Ti3O12 nanocomposite with an orthorhombic lattice with the crystal space group Fmmm.

Optical and structural characterizations of NiO-doped PMMA films and fabrication of Ag/NiO-doped PMMA/n-Si/AuSb for analogue-digital switching applications

Herein, the authors report the NiO-doped PMMA nanocomposites fabrication process with different Ni concentrations of 0.001–10 wt% on pre-cleaned glass, ITO, and n-type Si via spin-coating technique. X-ray diffraction (XRD) was used to analyze the crystal structure of NiO in powder form and the NiO-doped PMMA nanocomposite thin films. The Rietveld refinement method was used to analyze the manufactured NiO's powder-form structural characteristics. The analysis data revealed a single phase of NiO nanoparticles with face-centred cubic of Fm-3m space group. The average crystallites' mean size and the microstrain value were determined based on the Williamson-Hall model and were equal to 32.47 ± 1.210 nm and 5 × 10−5, respectively. The FESEM micrographs illustrate dispersed cubic-shaped NiO grains in the PMMA matrix. The estimated energy gaps and the width of the localized energy states (Urbach tails) are plotted against the photon energy. The estimated energy gap, EgOp is increasing from 3.649 ± 0.003 eV to 3.782 ± 0.005 eV with increasing the NiO nanoparticles' doping ratio in the PMMA as a host insulating polymer. The fabricated Ag/NiO-PMMA (S4)/n-Si/AuSb heterojunction device revealed two different (HRS and LRS) resistance-switching behaviours. For second and third electrical (I–V) paths, the extracted magnitudes of the ideality factor are 2.397 ± 0.006 and 2.691 ± 0.003 and the calculated barrier height are 0.727 ± 0.004 and 0.886 ± 0.005, respectively. The interfacial electronics states NSS increasing from 6.58 × 1012 to 3.7 × 1014 cm−2.eV−1 and 3.48 × 1013 to 3.65 × 1014 cm−2 .eV−1 for the 2nd HRS path and 3rd LRS, respectively. The investigated hysteresis loop and the variation in interfacial electronics states reveal that the NiO-PMMA nanocomposite may be promising in non-volatile memory and electrical switching electronic devices.

Unveiling the optoelectronic characteristics of SnTe thin films: An extensive investigation via structural & photoresponse analysis of drop-cast deposition

Thin film on a glass slide substrate of tin telluride (SnTe) is deposited at room temperature by drop casting method. The thin films are thoroughly characterized. The study by diffraction of X-ray and Raman stated the crystalline structure and SnTe phase of the films. The films have a cubic structure with space group of Fm-3m. The Raman spectrum showed A1 and ETO vibration modes corresponding to SnTe. The microstructure study is done by optical and scanning electron microscopy. The atomic force microscopy stated the thin film to be flat having uniform even spread. The transmission electron microscopy at high-resolution supported the crystalline nature of the thin films. The spacing of fringes matched the SnTe primary crystallographic (200) plane spacing. The photoresponse of the SnTe thin film is investigated at three intensities keeping +50 mV biasing voltage. The photoresponse analysis showed the drop-casting deposited SnTe thin film offers potential for future applications.

Rare coexistence of disorder-induced Griffiths phase and reentrant spin-glass state in a Heusler alloy Rh2FeAl with high Curie temperature

In this work, we report the synthesis of a Heusler alloy Rh2FeAl with valence electron count (VEC) 29 forming in B2-type structural disorder, where Fe atoms are distributed randomly with Al atoms between 4a and 4b Wyckoff positions (space group Fm3¯m, No: 225). Despite the structural disorder among the moment carrying Fe atoms, the compound exhibits ferromagnetic Curie temperature around TC ∼ 497 K. Nevertheless, the observation of Griffiths-phase (GP) like behaviour at TG ∼ 592 K suggests that atomic disorders brought down the bulk TC by about 95 K. The structural disorder also affects the ordered spin arrangements below TC through the development of a reentrant spin glass (RSG) state at low temperature. Both the GP like behaviour as well as RSG states are rarely observed in Heusler alloys while their coexistence is even rarer. The isothermal magnetisation as well as temperature dependence of resistivity behaviour ruled out the possibility of having half-metallic ferromagnetic characteristic in this material.

Formation of PbS microstructured films by CBD method and study of structural properties

Microcrystalline lead sulfide (PbS) films were synthesized using the chemical deposition method. The films were deposited on pre-cleaned glass substrates and polished silicon wafers. Chemicals of high purity were utilized in the process. The morphology, composition, and structure of the films were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction (XRD). The films exhibited a galena phase with a face-centered cubic structure belonging to the Fm-3m space group. The average grain size was determined using the WilliamsonHall method, revealing a homogenous structure. Raman spectroscopy further confirmed the structural integrity of the films. The obtained results contribute to the understanding of the synthesis and properties of microcrystalline PbS films.

Single crystals and optical ceramics based on solid solutions of AgCl – AgBr – AgI system

The development of infrared (IR) and terahertz (THz) optical materials is work, that is connected with prospective applications in wide-spectral systems, medicine, IR and THz techniques. This work is focused on the development of new optical materials based on silver halides in the AgCl – AgBr – AgI system, selection of technological modes, preparation of single crystals and optical ceramics and investigation of their optical properties. The phase diagram of the AgCl – AgI system was refined, and a new phase diagram of AgCl – AgBr0.7I0.3 was investigated and constructed. In both diagrams, homogeneity and heterogeneity regions were found. In the AgCl – AgI diagram, the homogeneity region covers the concentration range from 0 to 7 mol. % AgI in AgCl, and the heterogeneity region from 7 to 98 mol. % AgI in AgCl. The phase diagram of AgCl – AgBr0.7I0.3 shows two regions of homogeneity in the concentration ranges of 0–49 and 78–100 mol. % AgBr0.7I0.3 in AgCl and one heterogeneous region from 47 to 87 mol. % AgBr0.7I0.3 in AgCl. In both systems in the regions of homogeneity it is possible to grow single crystals of the cubic NaCl crystal structure, space group Fm3m. For compositions of heterogeneous regions, it is possible to synthesize two-phase optical ceramics based on the cubic phase Fm3m and the hexagonal β-modification of AgI of wurtzite type (P63mc). The results of studies of phase diagrams of AgCl – AgI and AgCl – AgBr0.7I0.3 allowed us to determine the concentration ranges in the quasi three-component isothermal section of the AgCl – AgBr – AgI system. The obtained results allowed us to determine the compositions and select optimal technological modes, according to which single crystals of AgCl0.85Br0.10I0.05, AgCl0.72Br0.19I0.09, AgCl0.58Br0.29I0.13, AgCl0.97I0.03 and AgCl0.94I0.06 compositions were grown and optical ceramics of AgCl0.14Br0.60I0.26 composition were synthesized. The structure of the materials was determined by SEM analysis. The studied transmission ranges showed that single crystals and optical ceramics transmit radiation in the range from 0.48 to 41.7 μm and more with a maximum transparency level of up to 83 %. There are no absorption windows in the transmission spectra of the materials, which allows the developed optical materials to be used in the specified spectral ranges as transmission optics.

Effects of Bi2O3 doping on structural and electrical properties of Ce0.8Sm0.2O1.9 electrolyte for solid oxide fuel cells

The study investigates the impact of Bi2O3 doping on the crystal structure, density, and ionic conductivity of Ce0.8Sm0.2O1.9, a type of samarium-doped ceria oxide (SDC). The material is intended for use as a solid electrolyte in intermediate temperature solid oxide fuel cells (IT-SOFCs). The SDC-based electrolyte was created using the auto-combustion technique, with various molar ratios of Bi2O3. Phase compositions, microstructure, and ionic conductivity of all ceria ceramics were analysed using XRD, SEM and impedance analyses, respectively. The language is formal, clear, objective, and value-neutral, using high-level, standard language with consistent technical terms. Grammar, spelling, and punctuation are correct. Consistent citation and footnote style are maintained. The samples are single-phase ceramics that crystallise into a cubic fluorite type structure with space group Fm-3 m, as confirmed by the X-ray diffraction pattern. Technical abbreviations are explained. The structure ensures a logical flow of information with causal connections between statements. No filler words or biased language are used. SDC/Bi2O3 composite powders exhibit high sintering activity. The relative density of all samples sintered at 1300 ºC for 5 h was more than 96%, which is higher than that achieved by pure SDC electrolyte sintered at 1400 ºC (94.06%). Electrochemical performance results demonstrate that adding an appropriate amount of Bi2O3 can significantly enhance the conductivity of SDC materials. The SDC-based electrolyte containing 9 mol% of Bi2O3 (SDCB9) demonstrates the maximum conductivity of 43.5 mS·cm−1 at 800 °C, surpassing that of pure SDC which measures 26.86 mS·cm−1.

New Route to Synthesize High-Entropy Carbide Powders by Mechanical Alloying

A new route for the synthesis of the (NbTa)0.67\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.67}$$\\end{document}(TiHfZr)0.33\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.33}$$\\end{document}C and (NbTa)0.67\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.67}$$\\end{document}(MoHfW)0.33\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$_{0.33}$$\\end{document}C high-entropy carbides powders by mechanical alloying is presented. Namely, pure metal powders were wet-milled in toluene using a planetary mill under an argon atmosphere. The synthesized materials crystallize with a rock-salt structure (space group Fm3¯m\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$Fm{\\bar{3}}m$$\\end{document}). A significant reduction in structural defects with annealing of the samples was detected with X-ray diffraction and positron annihilation experiments. Simultaneously, only simple metallic properties without any trace of magnetic or superconducting phase transitions were observed.

Thermochemical Study of Bismuth Cobalt Dysprosium Oxide: The Enthalpy of Formation and Lattice Enthalpy

Bismuth cobalt dysprosium oxide of composition Bi12.5Dy1.5CoO22.325 has been prepared by solid-state reactions. The compound has a cubic structure (space group Fmm) with the unit cell parameter a = 0.55279(5) nm. The solution enthalpy and standard enthalpy of formation of Bi12.5Dy1.5CoO22.325 have been measured by solution calorimetry: ΔsolH0 = −1017.0 ± 7.5 kJ/mol, and ΔfH0 = −5338.8 ± 19.9 kJ/mol. The lattice enthalpy has been calculated using the Born–Haber cycle: ΔlatH0 = −99020 kJ/mol. The lattice enthalpy increases in magnitude as the lanthanide radius decreases in the neodymium–dysprosium–holmium series.