Md. Atikur Rahman

The structural, elastic, electronic and optical properties of MgCu under pressure: A first-principles study

The effect of pressure on the structural, elastic and electronic properties of the intermetallic compound MgCu with a CsCl-type structure have been investigated using ab-initio technique. The optical properties have been studied under normal pressure. We have carried out the plane-wave pseudopotential approach within the framework of the first-principle density functional theory (DFT) implemented within the CASTEP code. The calculated structural parameters show a good agreement with the experimental and other theoretical results.

First principles investigation of structural, elastic, electronic and optical properties of ABi2O6 (A = Mg, Zn) with trirutile-type structure

Abstract First principles calculations based on density functional theory with generalized gradient approximation are performed to investigate the structural, elastic, electronic, and optical properties of new bismuth oxides, ABi2O6 (A = Mg, Zn) with the trirutile-type structure. Initially, the geometry structures obtained by geometry optimization are consistent with the experimental values. The calculated structural parameters show a good agreement with the experimental results. The optimized lattice parameters, six independent elastic constants (C11, C12, C13, C33, C44 and C66), bulk modulus (B), shear modulus (G), Young’s modulus (Y), Pugh’s ratio (G/B), Poisson’s ratio (ν), and elastic anisotropy (A) are calculated and discussed. This is the first quantitative theoretical prediction of the electronic, elastic, and optical properties of these compounds. The investigation of the electronic band structures reveals that these compounds are electrical conductors, with contribution predominantly from the Bi 6p states. The analysis of the elastic constants and other moduli shows large anisotropy on elasticity and brittle behavior. The origins of features that appear in different optical properties of these two compounds have been discussed using band structures. The large reflectivity of the predicted compounds in the low energy region might be helpful in high-quality candidate materials for coating to avoid solar heating.

Investigation of the physical properties of two Laves phase compounds HRh2 (H = Ca and La): A DFT study

Structural, elastic, electronic and optical properties of laves phase intermetallic compounds CaRh2 and LaRh2 prototype with MgCu2 are investigated by using the first principle calculations. These calculations stand on density functional theory (DFT) from CASTEP code. The calculated lattice parameters are consistent with the experimental values. The significant elastic properties, like as bulk modulus, shear modulus, Youngs modulus and the Poissons ratio are determined by applying the Voigt Reuss Hill (VRH) approximation. The analysis of Pughs ratio shows the ductile nature of both the phases. Metallic conductivity is observed for both the compounds. Most of the contribution originates from Rh 4d states at Fermi level in DOS. The study of bonding characteristics reveals the existence of ionic and metallic bonds in both intermetallics. The study of optical properties indicates that maximum reflectivity occurs in low energy region implying the characteristics of high conductance of both the phases. Absorption quality of both the phases is good in the visible region.

Pressure-dependent mechanical and thermodynamic properties of newly discovered cubic Na2He

Abstract Recently for the first time, a stable compound of He and Na (Na2He) is predicted at high pressure. We explore the pressure-dependent elastic, mechanical and thermodynamic properties of this newly discovered Na2He by using ab initio technique. The calculation presents good accordance between the theoretical and experimental lattice parameters. Though the most stable structure of Na2He is found at 300 GPa, present study ensures the mechanical stability of this compound up to 500 GPa. The study of Cauchy pressure, Pughs ratio, and Poissons ratio implies the ductile manner of Na2He up to 500 GPa. According to the value of Poissons ratio the bonding force exists in Na2He is central. The study of Zener anisotropy factor indicates that Na2He is an anisotropic material but near at 300 GPa approximately isotropic nature of Na2He is revealed. The study of the bulk modulus, shear modulus, Youngs modulus and Vickers hardness implies that the hardness of Na2He can be improved by applying external pressure. However, the Debye temperature, melting temperature and minimum thermal conductivity of Na2He are also calculated and discussed at different pressures.

The structural, elastic and optical properties of ScM (M = Rh, Cu, Ag, Hg) intermetallic compounds under pressure byab initiosimulations

The influence of pressure on the structural and elastic properties of ScM (M = Rh, Cu, Ag, Hg) compounds has been performed by using ab initio approach pseudopotential plane- wave method based on the density functional theory within the generalized gradient approximation (GGA). The optical properties have been investigated under zero pressure. It is found that the optimized lattice parameters for all metals are in good agreement with the experimental data and other available theoretical values.

Theoretical investigation on MgV2O6: ab-initio study

Abstract DFT-based ab-initio calculations have been performed to study the mechanical, structural, electronic, optical and thermodynamic properties of Mg-based vanadium oxide MgV2O6. The evaluated unit cell parameters exhibit satisfactory agreement with the available experimental data. The second-order elastic constants and the other relevant quantities such as the shear modulus, Young’s modulus, Poisson’s ratio, compressibility, anisotropy factor, sound velocity and the Debye temperature have been calculated. After analysing the calculated elastic constants, it is shown that the compound under study is mechanically stable. The analysis of the electronic band structure shows that this compound reveals semiconducting nature with band gap 2.195 eV. Most of the contribution predominantly comes from O-2s states. Furthermore, in order to get deep insight into the optical transitions of MgV2O6, the refractive index, complex dielectric function, reflectivity, loss function, absorption coefficient and the photoconductivity are computed and discussed in details. Also we have computed the Debye temperature , using our calculated elastic constants data.

Ab-initio study of C15-type Laves phase superconductor LaRu2

Abstract Structural, elastic, electronic, optical, thermodynamic, and superconducting properties of the Laves phase superconductor LaRu2 with Tc ~ 1.63 K were investigated using the first-principles calculations for the first time. The corresponding evaluated structural parameters are in good agreement with the available theoretical values. The different elastic properties like as, elastic constants, bulk modulus B, shear modulus G, Young’s modulus E, and Poisson ratio ν were calculated using the Voigt–Reuss–Hill approximation. The ductility nature appears in both values of Cauchy pressure and Pugh’s ratio. The band structure and Cauchy pressure shows that the material behaves metallic nature. The calculated total density of state is 6.80 (electrons/eV) of LaRu2. The optical properties such as reflectivity, absorption spectrum, refractive index, dielectric function, conductivity, and energy loss spectrum are also calculated. The photoconductivity reveals the metallic nature of LaRu2 and absorption coefficient is good in the infrared region. The evaluated density and Debye temperature are 9.55 gm/cm3 and 110.51 K, respectively. In addition, the study of thermodynamic properties like as minimum thermal conductivity, melting temperature, and Dulong–Petit limit are 0.26 (Wm−1 K−1), 1,471.65 K, and 74.80 (J/mole K), respectively. Finally, the investigated electron-phonon coupling constant is 0.66 of LaRu2 superconductor.

Ab initio study on structural, elastic, electronic and optical properties of cuprate based superconductor

Abstract The structural, elastic, electronic, and optical properties of BaCuO2 are investigated using the plane-wave ultrasoft pseudo-potential technique, which is based on the first-principle density functional theory (DFT) with generalized gradient approximation (GGA). The calculated structural parameters show a good agreement with the experimental and other theoretical results. The optimized lattice parameters, independent elastic constants (C11, C12, C13, C33, C44, and C66), Bulk modulus B, compressibility K, Shear modulus G, and Poisson’s ratio ν, as well as the band structures, total and atom-projected densities of states and finally the optical properties of BaCuO2 has been evaluated and discussed. The band structure and density of states show that these phases have metallic behavior and the major contribution comes from O-2P states for BaCuO2. Further, the first time investigated optical functions reveal that the reflectivity is high in the IR-UV region up to 28.5eV for BaCuO2 respectively, showing this to be a promising coating material.

Synthesis and characterization of high-quality cobalt vanadate crystals and their applications in lithium-ion batteries

Abstract High-quality cobalt vanadate crystals have been synthesized by solid-state reaction route. Structure and morphology of the synthesized powders were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared (FT-IR) spectroscopy. The XRD patterns revealed that the as prepared materials are of high crystallinity and high quality. The SEM images showed that the crystalline CoV2O6 material is very uniform and well separated, with particle (of) area ~252 μm. The electronic and optical properties were investigated by impedance analyzer and UV–visible spectrophotometer. Temperature-dependent electrical resistivity was measured using four-probe technique. The crystalline CoV2O6 material is a semiconductor and its activation energy is 0.05 eV.