Calculated Lattice Parameters Research Articles

Insight into the Physical Properties of the Chalcogenide XZrS3 (X = Ca, Ba) Perovskites: A First-Principles Computation

AbstractThis study investigates the structural, mechanical, optical, thermal, and electronic properties of the ionic semiconducting materials XZrS3 (X = Ca, Ba) within the framework of density functional theory (DFT). Here, the elastic constants, modulus (bulk, shear, Young's), ratios (Pugh, Poisson) and elastic anisotropy for XZrS3 (X = Ca, Ba) are studied. Furthermore, the electronic, optical, and thermal properties for XZrS3 (X = Ca, Ba) are regenerated and designed using the values obtained with Cambridge Serial Total Energy Package (CASTEP) software. The calculated lattice parameters show excellent agreement with theoretical and experimental values. The elastic stiffness constants confirm the mechanical stability of both compounds. Although XZrS3 (X = Ca, Ba) is elastically anisotropic, it has little optical anisotropy. The electronic band structures of the material exhibit direct-bandgap semiconducting behavior, with values of 1.3 eV (CaZrS3) and 1.1 eV (BaZrS3) using the generalized gradient approximation (GGA), respectively, which is ideal for solar cell (0.9–1.56 eV) and optoelectronic device applications. Bandgap values of 1.9 eV and 1.6 eV are found for CaZrS3 and BaZrS3, respectively, using the Heyd–Scuseria–Ernzerhof HSE06 functional, which is consistent with previous theoretical and experimental bandgap results. The optical properties including dielectric function, refractive index, absorption coefficient, reflectivity, and loss function are characterized using the GGA of Perdew–Burke–Ernzerhof (GGA-PBE) and HSE06 methods and are discussed in detail. Because of the relatively low Debye temperature (D), thermal conductivity of the lattice (kph), and minimum thermal conductivity (Kmin), the studied materials can be used as thermal barrier coating (TBC) materials. The capacity of heat, Debye temperature, and thermal coefficient of expansion are all computed.

Significant improvement in structural, electronic, optical and thermoelectric properties of PdTe2 in bulk and monolayer phase: A G0W0+BSE approach

Using first principles calculations structural, electronic, thermoelectric and optical properties of PdTe2 in bulk and monolayer were investigated. The calculated lattice parameters with different exchange correlation functionals show that the results obtained with addition of van der Waals corrections (vdW-DFC09x) are very well matched with the results obtained experimental. For correct prediction of electronic band gap, G0W0 approximation is used and the calculated band structure reveal that PdTe2 in bulk form has metallic nature as attained in experimental studies. In addition, the electronic band gap results with G0W0 approximation depicted that PdTe2 in monolayer phase is a semiconductor material with a direct band gap of 1.12 eV. The optical spectra have been calculated via many-body perturbation theory (MBPT) by solving Bethe-Salpeter equation (BSE) (G0W0+BSE). Ultimately, the results of optical spectra demonstrated that PdTe2 in monolayer phase has strong optical absorption within visible light wavelengths than the bulk phase which is good for solar cell applications. Thermoelectric (TE) properties of PdTe2 in bulk and monolayer structures have been studied using BoltzTraP code. The TE properties calculations indicated that better performance can be obtained by reducing the dimensionality of materials. The figure of merit was found to be above unity for monolayer phase. This paper successfully exploited the enhancement of the figure of merit values with the monolayer structure of PdTe2 material.

Structural, elastic, mechanical, and electronic properties of chalcogenide perovskite SnZrS3 under pressure

In this paper, we have presented the structural, elastic, mechanical, and electronic properties of the transition metal chalcogenide perovskite SnZrS3 under different pressures by using first-principles method. Our calculated lattice parameters at ambient pressure are in good agreement with the experimental and previous theoretical results. The elastic constants were evaluated numerically for orthorhombic SnZrS3 using the strain-stress approach. Orthorhombic SnZrS3 shows a strong anisotropic behavior of the elastic and structural properties. According to the calculations of the electronic properties, we find the states near the valence band top are derived from S 3p, Zr 4d, Sn 5p, and Sn 5s orbitals, and the lowest conduction band is composed of Zr 4d, S 3p, and Sn 5p orbitals. As the pressure increases, the conduction and valence band shift to lower and higher energies, respectively. These results indicated that lattice constants and band gap decrease with the increase of pressure.

First-principles investigation on structural, thermodynamic, and elastic properties of suboxide Zr3O phase

The lattice dynamics and finite-temperature thermodynamic and mechanical properties of three Zr3O polymorphs, including rhombohedral (R3−c), rhombohedral (R32), and hexagonal (P6322) phases, were theoretically investigated using the first-principles calculations. The calculated lattice parameters agree well with experimental values. It is confirmed that the three Zr3O phases exhibit both dynamic and thermodynamic stability. The entropy, enthalpy, Gibbs free energy, specific heat capacity, thermal expansion coefficient, and elastic modulus as a function of temperature from 0 to 1500 K were systematically evaluated. It is found that Zr3O (R3−c) is the ground state at 0 K followed by Zr3O (R32) and Zr3O (P6322). Structural phase transitions occur from Zr3O (R3−c) to Zr3O (R32) at 50 K and then to Zr3O (P6322) at 540 K. Zr3O (R32) displays superior mechanical properties compared to the other two Zr3O phases.

Hydrogen Storage Capacity of Lead-Free Perovskite NaMTH3 (MT=Sc, Ti, V): A DFT Study

Hydrogen is a promising clean energy carrier, but its storage is challenging. In this study, we investigate the potential of NaMTH3 (MT=Sc, Ti, V) hydride perovskite as solid-state hydrogen storage material. Using density functional theory (DFT), we comprehensively analyze their structural, hydrogen storage, phonon, electronic, elastic, and thermodynamic properties. Mechanical stability is assessed through calculation of lattice parameters, bulk and shear moduli, Poisson’s ratio, and Young’s modulus based on elastic constants. All three hydrides were found to be stable mechanically. Furthermore, the anisotropy factor was also investigated. Results show that the investigated hydrides are brittle and metallic. Their metallic character is due to the significant interplay between phonons and electrons. We also investigated their enthalpy, entropy, free energy, Debye temperatures, and specific heat capacities to investigate thermal stability.

Topological semimetals in the ZrB5 (B = Se, Te) material class: Weyl points and electronic properties

In the present work, the electronic structure, elastic parameters, density of states (partial and total), optical properties, and charge density of ZrB5 (B = Se, Te) have been investigated by means of first principles calculations. The generalized gradient approximation has been used for modeling the exchange-correlation effects. It has been observed that the calculated lattice parameter values are in agreement with the values in the literature. The second-order elastic constants were calculated, and the other related quantities have also been estimated. The electronic band structures and the partial density of states corresponding to these band structures of ZrSe5 and ZrTe5 are examined, and it is understood that ZrTe5 and ZrSe5 are narrow band semiconductors or semimetals. Finally, the electron energy loss function (ELS) spectra and charge density of ZrB5 are calculated and interpreted.

Electro-optical characterization of rare earth doped CuInS2 thin films synthesized by CBD

This work aims to study the electrical and optical properties of CuInS2 thin films to see the impact of rare earth doping on the properties of films obtained by Chemical bath deposition (CBD) in alkaline medium at 80 °C bath temperature. The observed and calculated lattice parameters are in good agreement with each other as confirmed from structural studies. Hall mobility and other parameters were calculated. The mobility of Pr doped film was quite high. E = hν = hc λ has been used to calculate the band gaps of various doped films of CuInS2. It is found that band gap is low for Sm doped film. This could be due to small particle size. Presence of dopant has been confirmed from EDS. PC studies has been done to know about the possible states in band gap. The photoconductive gain is high in Sm doped film. The emission spectrum were recorded for the wavelength 300–1000nm. The peak sharpness in terms of intensity is very high in Sm doped films. Spherical shape particles are prominently appeared on the surface of the film.

Investigate the effect of hydrothermal temperature on the structure and characterization of 20 % ZnO-Cu2O nanocomposite

The ZnO with 20 mol.% was hybridized with Cu2O to fabricate nanocomposites (20 % ZnO-Cu2O (ZC NCs)) were prepared by hydrothermal method at the investigated temperatures of (120, 200 and 250) ℃. The structural properties and characterization of the materials were investigated by physical measurements including: XRD, SEM, EDX and solid sample UV-Vis spectra. The results showed that the fabricated material samples consist of two crystalline phases (ZnO wurtzite and Cu2O octahedra) with calculated lattice parameters that were suitable for each type of crystal of the material. The average crystal sizes of the ZC120, ZC200 and ZC250 samples were (20.08, 20.36 and 22.50) nm respectively, which were grown lager when the hydrothermal temperature increase. The optical bandgap energy (Eg) of the ZC120, ZC200 and ZC250 material samples was determined to be (2.51, 2.52 and 2.56) eV, respectively. These Eg values of the fabricated ZC NCs samples were intermediate between the two types of ZnO (Eg ~ 3.37 eV) and Cu2O (Eg ~ 2.17 eV) materials, and was valid in the excitation region of visible light. ® 2023 Journal of Science and Technology − NTTU

Crystallographic Benchmarking on Diffraction Pattern Profiling of Polymorphs-TiO2 by WPPF for Pigment and Acrylic Paint

At a very low temperature high crystalline phase of TiO2 best-fitted strain anatase was synthesized by peptization which was the prime object of this study. Unresolved parameters were investigated by the X-ray diffraction (XRD) technique employed for lattice parameters, crystallite size, lattice volume, strain, crystal structure, d-spacing and percentage of phase in weight fraction. 54.40 % anatase, 29.10 % brookite and 16.50 % rutile crystalline phase were found by whole powder pattern fitting (WPPF-Rietveld’s refinement) method and lattice volume of anatase 137.150, brookite 267.079 and rutile 62.901 ų as well the crystal strain 0.307, 0.45 and 0.28 % of anatase, brookite and rutile polymorph-TiO2 found respectively. The calculated lattice parameters of the anatase are \(\alpha\)=\(\beta\)=\(\gamma\)= 90.0°; a=b= 3.8056 Å, c= 9.470 Å and predominant (101), (004) and (200) miller indices with diffracted angle (2Ɵ) 25.38, 37.26 and 48.22 observed. The average crystallite size was 7.39 nm which confirmed the formation of nano-crystal-TiO2 due to the highly dispersed on medium. The percentage of strain of the individual polymorphs of TiO2 shows the best fit used for the pigment and acrylic paint.

Theoretical study on the elastic and thermodynamic properties of CdS

The physical properties of CdS is calculated by using the first principles pseudopotential plane wave method based on density functional theory (DFT). The calculated lattice parameters and elastic constants agree well with other theoretical values, and the crystal is determined to be structurally stable by the Born mechanical stability condition. The Debye temperature, Grüneisen parameters, heat capacity and thermal expansion coefficient of CdS under high temperature and high pressure were studied successfully by using the quasi-harmonic Debye model. The influence of pressure on thermal expansion coefficient and Debye temperature is greater than that of temperature. The heat capacity decreases with the increase of pressure. At high temperature and high pressure, the heat capacity approaches the Dulong-Petit limit.

Origin of the Magnetic-Optical Properties of Palladium Compounds, an Ab Intio Study

Abstract: The structural, magnetic, and magneto-optical properties of the PdM (M=Fe, Co, Ni) alloy are investigated using first-principles calculations with the exciting code. The study employs the full potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). The exchange-correlation energy is described in the generalized gradient approximation developed by Perdew-Burke-Ernzerhof (PBE-GGA). The calculated lattice parameters are in good agreement with theoretical and experimental results. The magnetic properties reveal a ferromagnetic stability phase for all compounds. Additionally, the total (TDOS) and partial (PDOS) density of states, along with the band structure, indicate that PdM (M = Fe, Co, Ni) exhibits metallic behavior. The total and local magnetic moments are investigated. We conducted a study on the polar magneto-optical Kerr effect and calculated Kerr spectra. The microscopic origins of the peaks found in Kerr's angle are interpreted as interband transitions, primarily arising from the states (d to d) in the PdNi and (S to d) in the PdFe and PdCo alloys. Keywords: P-MOKE, DFT, GGA-PBE, Intermetallic.

(Digital Presentation) Fabrication and Characterization of 4Sc4YSZ/LSM-4Sc4YSZ Novel Electrode-Supported Half-Cell Composition for Solid Oxide Electrochemical Cells

Scandium and Yttrium co-doped ZrO2 (4Sc4YSZ) thin film solid electrolyte has exhibited improved conductivities and phase stability by considering advantages of both Y-doped zirconia (YSZ) and Sc-doped zirconia (ScSZ). To further investigate the promising properties of this co-doped composition, a solid electrolyte thin film of 4Sc4YSZ deposited on a new LSM-4Sc4YSZ composite electrode was conducted. In this study, the effect of pre-sintering temperature (1000°C, 1150°C, and 1300°C) of the LSM-4Sc4YSZ electrode substrate in the deposition of a dense solid electrolyte film was studied. X-ray diffraction (XRD) analysis of all the LSM-4Sc4YSZ composite electrodes revealed distinct phases of rhombohedral LSM and cubic 4Sc4YSZ. Also, the thin film electrolytes exhibited cubic 4Sc4YSZ with calculated lattice parameters of a equal to 5.10 Å, 5.10 Å, and 5.09 Å deposited on the electrode substrate pre-sintered at 1000°C, 1150°C, and 1300°C, respectively. The obtained lattice parameters were comparable with the reference LSM (PDF card no. 000-053-0058) and 4Sc4YSZ (PDF card no. 01-080-4524). Morphological characterization via scanning electron microscopy (SEM) showed that the thin film solid electrolyte with LSM-4Sc4YSZ electrode pre-sintered at 1300°C has a relatively dense microstructure than those with lower pre-sintering electrode temperatures. In addition, the thin film deposited on the 1300°C LSM-4Sc4YSZ obtained the lowest average thickness of 12.81 µm as compared to the 1000°C and 1150°C LSM-4Sc4YSZ with thickness values of 38.32 µm and 27.99 µm, respectively. The electrochemical performance of the fabricated half-cell was analyzed using electrochemical impedance spectroscopy (EIS). The total conductivity, as calculated from the EIS results, of 4Sc4YSZ/LSM-4Sc4YSZ half-cell pre-sintered at 1300°C is 0.0726 S/cm at 700°C under oxygen gas flow environment.

Theoretical and experimental study of the optoelectronic, thermodynamic and vibrational properties of the nanostructure of m-WO3

Tungsten trioxide (WO3), an n-type semiconductor, has attracted attention due to its diversity of properties, such as catalytic activity, gas sensing capabilities, photochromic behavior, and its ability to absorb both ultraviolet and visible light. This study aimed to investigate the monoclinic phase of the synthesized WO3 (m-WO3) through a combination of computational and experimental studies. We present the results of a theoretical investigation on m-WO3 using first-principles calculations (ab initio) and the pseudopotential model of plane waves. The Density Functional Theory (DFT) was employed, utilizing both the Local Density Approximation (LDA) and Generalized Gradient Approximation (GGA) to account for exchange potential and correlation effects. Structural properties, electron band structure, electron density of states, and optical properties (reflectivity and optical absorption) were computed for the optimized nanostructure at its lowest energy state. A comparison between the calculated lattice parameters and theoretical/experimental results revealed a good agreement. Furthermore, the thermodynamic potentials and specific heat at the constant volume of the nanostructure were calculated. Infrared (IR) and Raman spectra within the frequency range of 0–1000 cm−1 were estimated and assigned, and the results were compared with experimental data and demonstrated good agreement with the literature.

Electronic Structure Calculation of α-Al2X3 System (X = O, S) Based on R++Scan Functional

Due to the necessity of reducing the reliance on fossil fuels, several systems are considered to be alternative and/or additional support for the existing battery material. In this report, structural and electronic properties of aluminium oxide (Al2O3) and aluminium sulfide (Al2S3) with hexagonal symmetry (α-phase), are investigated by utilizing density functional theory technique based on r++SCAN functional. The calculated lattice parameter and insulating gap for both systems are well matched with previous experimental studies and display higher accuracy compared to the results from local density approximation (LDA) and generalized gradient approximation (GGA) studies. The calculated insulating gap values are 10.3 eV and 4.1 eV for α-Al2O3 and α-Al2S3 respectively. For α-Al2O3 system, we observed hybridized s-p-d orbital of Al-O in the conduction states, consistent with the interpretation of past X-ray Absorption Near Edge Structure (XANES) data. Finally, the bulk and young modulus for α-Al2O3 are determined to be 251 GPa and 423 GPa which is very close to the known experimental values of 280 GPa and 451 GPa.

Innovative development of hybrid nanocatalyst (ATH-ZnONPs) through green methods for achieving visible light-induced photocatalytic aerobic oxidation of benzyl alcohols into corresponding aldehydes and ketones

In recent research, there has been a surging interest in green methods for manufacturing metal oxide photocatalysts and enabling organic transformations in gentle conditions. This study achieved a groundbreaking development, introducing zinc oxide nanoparticles sensitized with anthocyanin dye (ATH-ZnONPs) for the very first time. The reducing agents in pomegranate leaves were utilized to synthesize ZnONPs from zinc salt. Simultaneously, anthocyanin dye was extracted from pomegranate flowers and linked with the ZnONPs. The FT-IR functional group analysis provided evidence of the successful conjugation of ZnONPs and ATH dye. SEM, EDX, and Elemental Mapping analysis unveiled the spherical morphology and nanocrystalline structure of ATH-ZnONPs, with particle sizes falling within the range of 50–70 nm. XRD analysis verified the hexagonal structural configuration of ZnONPs within the hybrid nanocomposite, with calculated lattice parameters of a = 3.261 Å and c = 5.207 Å. UV–Vis and DRS spectroscopy demonstrated that the composite efficiently harnesses visible light irradiation, exhibiting an energy bandgap of 2.22 eV. The assessment of ZnONPs through BET analysis unveiled a pore volume of 0.053 cm3/g, an SSA of 14.223 m2/g, and an average pore size of 4.18 nm, underscoring the mesoporous characteristics of ZnONPs. Importantly, the photocatalytic performance of the synthesized ATH-ZnONPs was thoroughly examined under blue LED light exposure. This investigation encompassed the evaluation of catalyst dosage, the impact of the light source, stability, regeneration, and the potential for reuse in the aerobic oxidation of benzyl alcohols, resulting in their corresponding aldehydes and ketones. 1HNMR and 13CNMR were used to characterize the products. The results of these studies highlight the versatile potential of this composite for a wide range of photocatalytic applications.

Densification and microstructural correlation with thermo-mechanical strength of TiO2-doped (Al1-xCrx)2O3 (x=0.1, 0.3) solid solution ceramics

In this work, TiO2-doped (Al1-xCrx)2O3 (x = 0.1, 0.3) ceramics were prepared in the range of 1600 °C–1700 °C under a slightly reducing atmosphere. The lattice parameter calculations only showed a minor increment with TiO2 doping, implying a meager solid-solubility limit (also detected by EDS semi-quantification). The grain size of (Al1-xCrx)2O3 is directly proportional to the TiO2 amount and sintering temperature. Beyond the TiO2 solid solubility limit, exaggerated grain growth and excessive pore formation were observed at higher sintering temperatures. The highest flexural strengths were observed without TiO2 at a higher sintering temperature and with 1 wt% TiO2 at lower sintering temperatures. However, higher TiO2 inclusion has deleterious effects on flexural strengths, as the failure occurs via a combined effect of porosity and larger grains.

Effect of Cu doping on structural and magnetic properties of Cu x Zn1-x Fe2O4 nanoparticles for biomedical applications

Nano-ferrites with chemical equation Cu x Zn1-x Fe2O4 (x = 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7) were prepared by sol–gel auto-combustion method to study structural and magnetic properties along with antibacterial and antifungal activity. The samples are sintered in air at 400 °C for 4 h. The samples are characterised by x-ray diffraction (XRD), ultraviolet (UV), Fourier-transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), energy dispersive X-ray (EDX), and vibrating-sample magnetometry (VSM) tools. Presence of some secondary phases are noticed in the samples. XRD data is utilised to calculate lattice parameter, crystallite size, lattice strain, and density of ferrite samples. The crystallite size varies between 6.3 and 7.7 nm and lattice strain has value between 0.11–0.15. Also, VSM is used to calculate saturation magnetisation, coercivity and remanent magnetisation of synthesised samples. The saturation magnetisation as high as 32.8 emu g−1 is obtained for x = 0.7 composition. The magnetic Cu x Zn1-x Fe2O4 nanoparticles have shown good antibacterial and antifungal activity.

Synthesis and characterization of copper ferrite nanocomposite from discarded printed circuit boards as an effective photocatalyst for Congo red dye degradation

The copper ferrite nanocomposite (CFN) was synthesized by solvothermal process in presence of leachate powder discarded printed circuit boards, ethylene glycol as a chelating agent, utilizing sodium hydroxide as precipitator at pH 12. The discarded PCBs contain excess amounts of precious metals, which makes them an attractive secondary resource. The synthesized CFN was characterized using XRD, SEM-EDS, UV–Vis, and FTIR. The transmission electron microscopy (TEM) showed that the copper ferrite particles are spherical shape with the crystallite size in the range of 20–50 nm. The calculated lattice parameters are in agreement with the described values such as average particle size of 19 nm and 8 nm for CFN-10 and CFN-20 respectively. The Kubelka-Munk plot showed bandgaps of 3.20 eV and 3.17 eV respectively. CFN-10 and CFN-20 exhibited notable photocatalytic degradation towards carcinogenic Congo red dye under UV-light irradiation with 86.48 and 96.19% degradation rates within 120 min. Rendering to the findings of this research work, the synthesis of copper ferrite nanocomposites has a great potential for Congo red dye breakdown, which makes it an effective, low cost and environmentally suitable solution for the clean-up of waste water.

Structural, electronic and magnetic properties RbRuO4 ; A theoretical study

Ruthenate oxide materials are significant compounds in magnetic technologies because they have an important element in transition metals. Herein we make a density functional theory (DFT) investigation to study the structural, electronic, and magnetic properties of rubidium ruthenium oxide RbRuO4. Gradient generalized approximation, GGA-PBE, and GGA-WC within Cohen-Sham equations were implemented in the CASTEP code and used in our calculations. Plane-wave pseudo potential method was used to simplify the electrons-Ions interactions. Results showed a ferromagnetic ground state of the material studied here. For the structural properties, RbRuO4 crystallizes in the orthorhombic structure (Pnma space group). In calculations of lattice parameters, we found a volume of primitive cells between 477 A°3 and 482 A°3 and bulk modulus between 82,12 GPa and 86,65 GPa. Finally, the band structure energies showed that RbRuO4 had a metallic nature.

Investigate the effect of hydrothermal temperature on the structure and characterization of 20 % ZnO-Cu2O nanocomposite

The ZnO with 20 mol.% was hybridized with Cu2O to fabricate nanocomposites (20 % ZnO-Cu2O (ZC NCs)) were prepared by hydrothermal method at the investigated temperatures of (120, 200 and 250) ℃. The structural properties and characterization of the materials were investigated by physical measurements including: XRD, SEM, EDX and solid sample UV-Vis spectra. The results showed that the fabricated material samples consist of two crystalline phases (ZnO wurtzite and Cu2O octahedra) with calculated lattice parameters that were suitable for each type of crystal of the material. The average crystal sizes of the ZC120, ZC200 and ZC250 samples were (20.08, 20.36 and 22.50) nm respectively, which were grown lager when the hydrothermal temperature increase. The optical bandgap energy (Eg) of the ZC120, ZC200 and ZC250 material samples was determined to be (2.51, 2.52 and 2.56) eV, respectively. These Eg values of the fabricated ZC NCs samples were intermediate between the two types of ZnO (Eg ~ 3.37 eV) and Cu2O (Eg ~ 2.17 eV) materials, and was valid in the excitation region of visible light.
 ® 2023 Journal of Science and Technology − NTTU