Lattice Parameters Research Articles

Phase equilibria of the Nb–Si-Gd ternary system at 1273K

The phase equilibria of the Nb–Si-Gd ternary system at 1273K in all the composition ranges were investigated by X-ray diffraction (XRD), electron probe microanalysis (EPMA), and Scanning electron microscopy (SEM) equipped with Energy dispersive spectroscopy (EDS). The isothermal section comprises 12 single-phase regions, 22 two-phase regions, and 11 three-phase regions. The existing of Nb3Si phase was confirmed at 1273K by couple diffusion. A new ternary compound Gd2Nb3Si4 was discovered and its crystal structure was analyzed by the Rietveld method with Rwp = 2.11%, Rp = 1.54%, Rexp = 0.75%. It belongs to the space group P41212 (No.92) with the lattice parameter a = b = 6.99048Å, c = 12.94393Å, α = β = γ = 90°.

Investigation of superconductivity of A15 type cubic Nb3Os material by using density functional theory

In this study, the structural, elastic, electronic, phonon and electron-phonon interaction properties of A15 type cubic Nb3Os compound were investigated by density functional theory. The lattice constant of this compound was obtained in agreement with experiments, and the investigation of elastic properties revealed its ductile nature. From electronic calculations for Nb3Os, the density of states at Fermi level (N(EF)) was found to be 5.31 states/eV with the largest contribution of Nb 4d orbitals. According to the results obtained from phonon calculations, Nb3Os was found to be dynamically stable in the cubic A15 structure and phonon modes were largely formed by the vibrations of Nb atoms. Using the electronic and phonon properties, we determined the Eliashberg spectral function, which illustrates the electron-phonon interaction. The electron-phonon interaction parameter and average phonon frequency values for Nb3Os were found to be 0.41 and 222.97 K, respectively. The calculated superconducting transition temperature of 1.05 K is in excellent agreement with the experimental value of 1.02 K.

Synergistic manipulation of physical properties of Ni-Mn-In-B alloys by atomic occupancy and magnetic states

The physical properties of the Ni-Mn-In-B alloys synergistically modulated by atomic occupancy and magnetic states are systematically investigated. The results indicate that B atoms are indirectly substituted at the Mn2 position in the Ni2Mn1.5In0.5 alloy (i.e., B→In→Mn2). When B is doped in interstitial positions, the B atoms tend to be closer to Mn atoms rather than In atoms. Additionally, the higher the concentration of Mn around the B atom, the lower the formation energy of the austenite (A) phase. The lattice parameters of the A phase decreases with increasing x content, while c/a and phase stability gradually decrease for the 4O, 6M, and NM martensites in the ferrimagnetic (FIM) state. The magnetostrain of the alloy shows an increasing trend with increasing B content due to the decrease in c/a resulting in a decrease in the tangent variable S= |c/a-a/c|; however, the elastocaloric properties decrease due to the decrease in the volume change ΔV/VA after the transformation. The Ni2Mn1.5-xIn0.5Bx (0≤x≤0.042) alloys undergo an A→6MFIM→NMFIM transformation. The total magnetic moment of the A phase decreases, whereas those of the 4O, 6M, and NM phases increase with increasing x content. The phase stability is explained by analyzing the total densities of states (TDOS) from an electronic structure perspective.

Experimental Investigation for the Preparation of Taro Leaf Nanoparticles by Sol-Gel Method and its Characterization

Abstract: In the present work, nano particles of Taro leaf were successfully synthesized chemically by modified Sol-gel method. Methanol is used as a solvent and buffers are added to take care for the homogeneity and PH value of the solution. Compared to micro particles, Nanoparticles have advanced characteristics and distinctly different properties. Taro leaf nanoparticles are one of the leaves nanoparticles which has varied and different properties when compared to other. Taro Leaf nanoparticles have considerable attention due to their attractive physical and chemical properties, Silver nitrate is taken as the metal precursor and sodium borohydride as a reducing agent. This preparation is simple, but the great care must be exercised to make stable particles. Here the Taro leaf nanoparticles are synthesized by sol gel process. Therefore the nanoparticles are characterized by the different techniques like SEM to find the size morphology and composition of leaf nanoparticles, XRD to know the lattice parameters. The peaks in the XRD pattern are in good agreement with the standard values.

Atomic and Electronic Structures of Co-Doped In2O3 from Experiment and Theory.

The synthesis and properties of stoichiometric, reduced, and Co-doped In2O3 are described in the light of several experimental techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), ultraviolet (UV)-visible spectroscopy, porosimetry, and density functional theory (DFT) methods on appropriate models. DFT-based calculations provide an accurate prediction of the atomic and electronic structure of these systems. The computed lattice parameter is linearly correlated with the experimental result in the Co concentration ranging from 1.0 to 5.0%. For higher Co concentrations, the theoretical-experimental analysis of the results indicates that the dopant is likely to be preferentially present at surface sites. The analysis of the electronic structure supports the experimental assignment of Co2+ for the doped material. Experiments and theory find that the presence of Co has a limited effect on the material band gap.

Gauge Field Marginal of an Abelian Higgs Model

We study the gauge field marginal of an Abelian Higgs model with Villain action defined on a 2D lattice in finite volume. Our first main result, which holds for gauge theories on arbitrary finite graphs and does not assume that the structure group is Abelian, is a loop expansion of the Radon–Nikodym derivative of the law of the gauge field marginal with respect to that of the pure gauge theory. This expansion is similar to the one of Seiler (Gauge theories as a problem of constructive quantum field theory and statistical mechanics, volume 159 of lecture notes in physics, Springer, Berlin, p v+192. https://doi.org/10.1007/3-540-11559-5, 1982) but holds in greater generality and uses a different graph theoretic approach. Furthermore, we show ultraviolet stability for the gauge field marginal of the model in a fixed gauge. More specifically, we show that moments of the Hölder–Besov-type norms introduced in Chevyrev (Commun Math Phys 372(3):1027–1058. https://doi.org/10.1007/s00220-019-03567-5, 2019) are bounded uniformly in the lattice spacing. This latter result relies on a quantitative diamagnetic inequality that in turn follows from the loop expansion and elementary properties of Gaussian random variables.

Investigation of Three‐Channel Heterostructure and High‐Electron‐Mobility Transistor with Quaternary In0.1Al0.5Ga0.4N Barrier

Herein, a high‐quality In0.1Al0.5Ga0.4N/GaN three‐channel (TC) heterostructure and the high‐electron‐mobility transistor (HEMT) based on it are proposed and investigated. The quaternary nitrides offer additional flexibility in adjusting the lattice constant and bandgap, enabling the achievement of a nearly strain‐free high‐Al‐content barrier. By stacking three In0.1Al0.5Ga0.4N/GaN heterostructures, a high 2D electron gas density of 2.59 × 1013 cm−2 and a high electron mobility of 1707 cm2 V−1 s−1 are achieved. As compared with the AlGaN/GaN TC heterostructure, the In0.1Al0.5Ga0.4N/GaN TC heterostructure reduces the sheet resistance by 39%, resulting in a 40 % reduction in the on‐resistance of the TC HEMT. Additionally, the inverse piezoelectric effect of the In0.1Al0.5Ga0.4N/GaN TC‐HEMT is investigated by negative‐gate voltage bias step‐stress experiments. During the stress experiments, no irreversible degradation is observed in the In0.1Al0.5Ga0.4N/GaN TC‐HEMT, while the AlGaN/GaN TC‐HEMT exhibits a significant deterioration beyond the critical voltage. The reliability related to the inverse piezoelectric effect of the devices can be further improved due to the lower stress in the lattice‐matched quaternary barrier.

Cd0.90Mn0.10Te single crystal for γ – Ray detector application: A comprehensive analysis of structural and compositional homogeneity

This study provides a comprehensive examination of the Cd0.90Mn0.10Te (CMT) single crystal in its role as a radiation detector. Covering aspects from the growth process to detector performance, the primary emphasis is placed on ensuring the uniformity of composition along the growth axis. A cost-effective custom-built vertical Bridgman (VB) setup is developed for the growth of highly homogeneous Cd0.90Mn0.10Te (CMT) single crystal. CMT single crystals of 10 mm diameter and 130 mm length with near uniform stoichiometry along the growth axis were grown using VB method. Laue diffraction confirms the single crystallinity of the grown crystal. The measured lattice constant is comparable to the theoretical value calculated using Vegard’s law. The two mode vibrations of the CdTe and MnTe sublattices were confirmed by Raman spectroscopy. The observed high optical transmittance in the mid-infra-red (IR) region and a nearly constant bandgap of ∼1.6 eV for the wafers taken at different locations along the growth axis reveals the IR transparency and compositional uniformity of the grown crystal. The energy dispersive X-ray spectroscopy proved that the elemental distribution is uniform in the grown crystal. The IR microscopic imaging shows Te inclusions with a number density in the range of ∼2.6–4.5 × 104 cm−2. The resistivity of the CMT crystal for all wafers was found to be in the order of 109 Ωcm. The γ–ray spectral resolution of ∼22 % of 59.5 keV irradiation from 241Am source is achieved.

Polyethylene glycol/melamine foam composite phase change materials modified by CdS/Ag exhibits high photothermal conversion performance

CdS has been shown to be an excellent photon trap with strong absorption of light at visible and near-infrared wavelengths. The use of CdS for phase change material (PCM) modification can significantly improve its photothermal conversion performance. However, due to the unique energy band structure of CdS, the difficulty in electron conduction leads to poor thermal conductivity. This problem can be improved by introducing high thermal conductivity nanometals for modification, however, the effective combination of CdS and nanometals has been challenging. In this study, a new preparation strategy is demonstrated, in which Ag nanoparticles (NPs) with similar lattice parameters and crystalline coordination to CdS is first introduced on the surface of carbonized melamine foam (CMF), followed by the introduction of CdS NPs. This similar structure helps to form a better interfacial bond between CdS and Ag. The resulting stabilized structure enables the composite phase change material (CPCM) to achieve 96.1 % PEG loading with an ultra-high photothermal conversion efficiency of 94.6 %, thermal conductivity of 0.61 W/m∙K, and excellent antimicrobial activity. This study provides valuable guidance for the engineering design of CPCM with high photothermal conversion performance and suggests its practical application value in seawater evaporation and thermal management of medical devices.

Controlling the physical properties of Ni1-xMnxFe2O4 multiferroic by the enhancement of ferroelectric phase through the increase of Mn content

The nanoparticles of the spinel ferrite system Ni1-xMnxFe2O4 with x = 0.0, 0.2, 0.4, 0.6, 0.8 and 1.0 were prepared using the auto combustion flash method technique, by using the nitrates as cations source and urea as a fuel agent for combustion. The XRD pattern validates the formation of cubic spinel structure of Ni1-xMnxFe2O4 nanoparticles and traces of hematite phase. By increasing the annealing temperature, the lattice parameter and crystallite size were increased. At various frequencies, the dielectric properties and initial permeability were measured as a function of temperature. The DC resistivity was found to have a linear relationship with temperature, with two regions and one break point at Curie temperature (TC). SEM and TEM analyses are used to investigate the morphology of the samples, as well as the size and shape of the crystallites. The samples' morphology revealed the formation of a uniform and spherical structural distribution. The material transfer to multiferroic at high Mn content accordingly the ferroelectric and ferrimagnetic properties appear, which give the ability of the material to become magnetoelectric material.

Exploring the multifaceted properties of novel oxide-based perovskites ABO3 (A=Nd and B[dbnd]Lr, Y): A DFT study

The full-potential linear augmented plane wave with local orbital (FP-LAPW) technique is now used in this approach to better understand the structural, electronic, optical and mechanical properties of simple cubic oxide perovskite. NdLrO3 and NdYO3 compounds are studied by employing the density functional theory (DFT) with CASTEP code for the first time. The lattice parameters are found 4.2462 and 4.2301 Å for NdLrO3 and NdYO3 respectively. Both the compounds have 1.9 eV and 1.4 eV band gap showing the direct band gap nature of both materials. The exchange-correlation (XC) energy has been selected during this investigation with the Local Density Approximation (LDA) approach. We optimize as well as clarify the elastic constants Cij, the bulk modulus B, elasticity modulus G, Young's modulus of stretch Y, and the Poisson ratio v. Every substance shows anisotropic behavior. NdLrO3 and NdYO3 compounds exhibit a direct band-gap nature, as revealed by the electronic band structure computations. These compounds were all classified as semiconductors. To quantify the number of localized electrons in various bands, partial density of states (PDOS) and total density of states (TDOS) were deployed. Both compounds are computed by fitting the dispersion relation of the imagined component. Optical properties showed that these compounds were excellent absorbers of incident radiation. Therefore, it may be assumed that these compounds could be employed in magnetic sensors because of anisotropic magnetic behavior and to capture the ultraviolet range of solar radiations.

Customization of Manganese Oxide Cathodes via Precise Electrochemical Lithium-Ion Intercalation for Diverse Zinc-Ion Batteries.

Manganese oxide-based aqueous zinc-ion batteries (ZIBs) are attractive energy storage devices, owing to their good safety, low cost, and ecofriendly features. However, various critical issues, including poor conductivity, sluggish reaction kinetics, and unstable structure still restrict their further development. Oxygen defect engineering is an effective strategy to improve the electrochemical performance of manganese oxides, but challenging in the accurate regulation of oxygen defects. In this work, an effective and controllable defect engineering strategy-controllable electrochemical lithium-ion intercalation - is proposed to tackle this issue. The incorporation of lithium ions and oxygen defects can promote the conductivity, lattice spacing, and structural stability of Mn2O3 (MO), thus improving its capacity (232.7mAhg-1), rate performance, and long-term cycling stability (99.0% capacity retention after 3000 cycles). Interestingly, the optimal ratio of intercalated lithium-ion varies at different temperature or mass-loading of MO, which provides the possibility to customize diverse ZIBs to meet different application conditions. In addition, the fabricated ZIBs present good flexibility, superior safety, and admirable adaptability under extreme temperatures (-20-100°C). This work provides an inspiration on the structural customization of metal oxide nanomaterials for diverse ZIBs, and sheds light on the construction of future portable electronics.

Local Structure, Structural, Vibrational, and Optical Properties of Natural Zircon

Structural properties of Indian metamict single zircon crystals are studied by comparing their properties with those of synthetic zircon synthesized via solid‐state reaction method, which serves as the standard. X‐Ray diffraction (XRD) data reveal changes in lattice parameters and the presence of strain, metamictization, etc. It is found that the degree of crystallinity is ≈63.8% indicating the simultaneous presence of crystalline and disordered regions. These changes are likely due to the presence of several radioactive/nonradioactive elements. The presence of such elements is observed and the sample composition is analyzed through total reflection X‐Ray fluorescence. XRD crystallographic data are further utilized as input for analyzing X‐Ray absorption spectroscopy data recorded around Zr central absorbing atom. X‐Ray absorption near‐edge structure shows slight modification in the white line feature and some disorder compared to the synthetic one. Reduced coordination number observed from extended X‐Ray absorption fine structure suggests the presence of disorder in local structure. Micro‐Raman spectroscopy indicates that crystalline behavior varies across different locations, suggesting that the sample has undergone varying degrees of metamictization, confirming a nonuniform distribution of elements. The work documents and analyses structural evolution within isolated silica tetrahedron network in association of Zr4+ cation as a function of self‐irradiation and recovery over millions of years and correlating the same with optical properties.

Transverse-momentum-dependent wave functions of the pion from lattice QCD

We present a lattice QCD calculation of the transverse-momentum-dependent wave function (TMDWF) of the pion using large-momentum effective theory. Numerical simulations are based on one ensemble with 2+1+1 flavors of highly improved staggered quarks with lattice spacing a=0.121 fm from the MILC collaboration, and one with 2+1 flavor clover fermions and tree-level Symanzik gauge action generated by the CLS collaboration with a=0.098 fm. As a key ingredient, the soft function is first obtained by incorporating the one-loop perturbative contributions and a proper normalization. Based on this and the equal-time quasi-TMDWF simulated on the lattice, we extract the TMDWF. The results for both lattice ensembles are compatible and a comparison with a phenomenological parametrization is made. Our studies provide a first attempt of calculation of TMDWFs which will eventually lead to crucial theory inputs for making predictions for exclusive processes under QCD factorization. Published by the American Physical Society 2024

First-principles screening of XSbF3 (X = Ba and Ra) fluoroperovskites: an insight into structural, optoelectronic and thermal properties

This work presents a computational study of the physical properties such as structural, electronic, optical and thermal properties of XSbF3 (X = Ba and Ra) fluoroperovskites. The calculations were performed using the density functional theory (DFT) calculations in conjunction with Quantum Espresso code. The stability of the crystal structure XSbF3 compounds is determined by binding energy (Eb) computations. The Eb values for BaSbF3 and RaSbF3 compounds are −19.25 and −20.04eV respectively, indicating that both studied compounds are stable. The optimized lattice constants for BaSbF3 and RaSbF3 compounds are 5.03 and 5.06 Å, respectively. The evaluation of electronic properties is conducted by electronic band structure, total density of states (DOS), and partial density of states (PDOS). It is observed from the PDOS plots that the p-states of Sb and F whereas the d-states of X atoms have the major contribution in the formation of the band structure. Various optical properties have been computed and compared. The static value of ε10 highlights the metallic nature of the studied compounds while RaSbF3 stands out for having the highest recorded value of ε20. The maximum nω values for BaSbF3 and RaSbF3 are 8.46 and 6.86 respectively indicating their potential for photoelectric applications. Furthermore when examining the properties it is evident that the BaSbF3 compound stands out as a material for energy storage because of its higher electron energy at 2.36 KJ/N.mol and lower electron free energy of −2.55 KJ/N.mol compared to the RaSbF3 compound. On the other hand, the RaSbF3 compound is an efficient material for catalysis due to its high ability to absorb heat energy from the external source, as compared to the BaSbF3 compound. This study is the first computational investigation of XSbF3 (X is Ba and Ra) compounds, which provides valuable insights into the physical properties of sb-based fluroperovskites and their potential applications.

Pressure‐Induced Structural, Electronic, and Optical Properties of Lead‐Free NaGeX3 (X = F, Cl, Br, and I) Perovskites: First‐Principles Calculation

AbstractIn this study, the pressure‐induced structural, electronic, and optical properties of lead‐free inorganic Ge‐based perovskite materials NaGeX3 (X = F, Cl, Br, and I) through density functional theory (DFT) simulations conducted are explored with CASTEP. This research is driven by identifying perovskite materials with a tunable bandgap that are both efficient and non‐toxic for solar cell applications. The materials under consideration are found to be mechanically and thermodynamically stable, as per the Born stability criteria and formation energy calculations. This band structure analysis indicates these compounds exhibit semiconducting behavior with a tunable bandgap. Under ambient conditions, the Ge─X and Na─X bonds display covalent and ionic characteristics, respectively. Substituting halogens from F to I increases lattice parameters and a more covalent nature of the Ge─X bond. Concurrently, the bandgap narrows, transitioning from indirect (F) to direct (Cl, Br, and I). At the same time, the static dielectric constant rises, and both absorption and conductivity are significantly enhanced with a redshift in the optical spectrum. The application of tensile stress (positive pressure) increases both the lattice constant and bandgap, whereas the dielectric constant, absorption, conductivity, and reflectivity decrease. Conversely, compressive stress (negative pressure) induces the opposite effect. Pressure‐induced variations in the bandgap highlight the potential of NaGeX3 materials to significantly impact the next‐generation solar cells’ development, offering a pathway to more sustainable and efficient energy solutions.

Anisotropic optical property of ferroelectric Bi2O2X(X = S,Se,Te) monolayer and strain engineering

Based on the first-principles calculations, ferroelectric Bi2O2X(X = S,Se,Te) monolayers with unequivalent in-plane lattice constants are confirmed to be the ground state, which is consistent with the experiment result (Ghosh et al 2019 Nano Lett. 19 5703–09), and the anisotropic optical property is firstly investigated. We find that the polarizations of Bi2O2X monolayers points along the direction of a-axis, and Bi2O2Te monolayer process the largest polarization. Furthermore, both the biaxial and uniaxial strains are favor for the enhancement of polarization of Bi2O2X monolayers. It should be mentioned that the type of band gap will convert from indirect to direct for Bi2O2Te monolayer when the a-axial tensile strain is larger than 2%. At last, the optical absorption coefficient for Bi2O2X monolayers are calculated, and we obtain that Bi2O2Te monolayer has the strongest optical absorption within the range of visible light, the anisotropy and possible strain engineering to improve the optical absorption are discussed in detail. Our findings are significant in fields of optoelectronics and photovoltaics.

Unlocking the secrets of pressure-driven physical properties of NaNbO3 perovskite-oxide: A computational insight

The current investigation presents the various pressure-induced properties such as structural, elastic, mechanical, optical, and electronic features of NaNbO3 across a pressure range of 0.0–100 GPa. Utilizing the CASTEP tool alongside GGA-PBE based on DFT, comprehensive calculations are conducted. The material displays an indirect energy bandgap, with its magnitude increasing from 1.633 to 2.223 eV under rising pressure. Analysis reveals a covalent character in O–Nb bonds, while O–O and Na–O interactions exhibit an ionic nature. As pressure rises, both lattice parameters and volume exhibit a tendency to decrease. Interestingly, the material exhibits anisotropic behaviour and maintains mechanical stability, transitioning from brittleness at 0.0 GPa to ductility between 10 and 100 GPa. Additionally, it demonstrates superhard characteristics at 0.0–20 GPa and progresses to an ultrahard state from 30 to 100 GPa. Optical properties display a trend of sharpening peaks with a slight shift towards higher energy in the curves. Notably, the material's indirect bandgap renders it suitable for prolonged photocatalysis applications.

Co-Ni spinel nanoparticles for energy storage applications: Composition, structural parameters and electrical properties

In the ambit of this investigation, we delved into the properties of (Co/Ni)Fe2O4 spinel nanoparticles (CNSNs) with a spectrum of Co/Ni ratios, delineated as Co1-xNixFe2O4, where x adopts values of 0.0, 0.3, 0.5, 0.7 and 1.0. The synthesis of these CNSNs was adeptly executed via the citrate precursor technique. This study meticulously examined the crystal structure and granular morphology by applying X-ray diffraction (XRD) and scanning electron microscopy (SEM). It was unequivocally determined that each specimen exhibited a homogenous phase. The lattice parameters for the synthesized CNSN compounds agreed with the mean ionic radii of the Co2+ and Ni2+ ions, mirroring their respective concentrations within the nanoparticles. Furthermore, an extensive analysis of the alternating current (AC) electrical properties was carried out, encompassing a broad frequency range from 1 kHz to 3 MHz and a wide temperature range from 303 to 423 K. The observed behavior of the electrical properties was thoroughly evaluated and elucidated, considering the chemical composition of each CNSN. The relationship between the frequency dependency of σac, έ and tanδ is congruent with the prevailing literature and theoretical constructs that elucidate the composite materials' conductivity and dielectric constant, comprising grains and grain boundaries. The present CNSN samples do not exhibit maximum peak for tanδ, potentially due to the wider range of frequencies used than the anticipated peak frequency. The samples' measured conductivity and dielectric constant values displayed a high degree of coherence, corroborating each other's findings. Literature corroborates that the escalation in ac-conductivity values with frequency intimates certainly that the prepared samples may herald promise for utilization in energy storage solutions, bolstering the synergistic efficacy observed. Another conceivable application of these CNSN materials could be their integration in microwave technologies, suggesting a broad scope for future technological advancements.

Optimization of radiation shielding efficacy through tuning the crystal lattice parameters: Case study of α-quartz

Crystal γ-ray radiation competence on α-quartz crystal up to 15 GPa pressure unveil structural-shielding properties coupling. With increasing pressure the average lattice axial length known as a, and b are decreased affecting the behavior of the observed LAC or HVL values. Via tuning the lattice parameters (4.914<a<4.470 Å) and unit cell volume (113.06<Vc < 89.10 Å3), we were able to optimize the α-quartz crystal shielding performance via adjusting the essential shielding parameters (i.e., (5.809<MAC<0.021 cm2/g), (3.10 × 1023<Neff< 3.74 × 1023 e/g), (10.32<Zeff<12.43), and (10.79<Zeq<11.56)). We find that the maximum value of LAC = 16.61 cm−1 occur at defined unitcell parameters (a = 4.535 Å, c = 5.170 Å c/a = 1.14419, and Vc = 92.09 Å3). Whereas, the LAC minimum value is 12.67246 cm−1 at a = 4.90232 Å, c = 5.38309 Å, c/a = 1.10149, and Vc = 110.91621 Å3). The same is applied on the HVL behavior. This report, confirmed that changing the crystal structural lattice parameters allows for a different chances between the incident radiation-unit cell interactions for a possible optimization against the γ-rays penetrations into the crystal's sub-structures.