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A Thorough Investigation of Electronic, Optical, Mechanical, and Thermodynamic Properties of Stable Glasslike Sodium Germanate under Compressive Hydrostatic Pressure: Ab Initio Study

Tue, 11 Jun 2024 00:00:00 GMT

Title: A Thorough Investigation of Electronic, Optical, Mechanical, and Thermodynamic Properties of Stable Glasslike Sodium Germanate under Compressive Hydrostatic Pressure: Ab Initio Study Authors: Lalhriatzuala Abstract: In this paper, we have tried to elucidate the variation of structural, electronic, and thermodynamic properties of glasslike Na2GeO3 under compressive isotropic pressure within a framework of density functional theory (DFT). The result shows stable structural (orthorhombic → tetragonal) and electronic (indirect → direct) phase transitions at P ∼ 20 GPa. The electronic band gap transition plays a key role in the enhancement of optical properties. The results of the thermodynamic properties have shown that Na2GeO3 follows Debye’s lowtemperature specific heat law and the classical thermodynamic of the Dulong−Petit law at high temperature. The pressure sensitivity of the electronic properties led us to compute the piezoelectric tensor (both in relaxed and clamped ions). We have observed significant electric responses in the form of a piezoelectric coefficient under applied pressure. This property suggested that Na2GeO3 could be a potential material for energy harvest in future energy-efficient devices. As expected, Na2GeO3 becomes harder and harder under compressive pressure up to the phase transition pressure (∼20 GPa) which can be read from Pugh’s ratio (kH) > 1.75, however, at pressures above 20 GPa kH < 1.75, which may be due to the formation of fractures at high pressure.

Theoretical Investigation of Lead Perovskite PbXO 3 (X=Ti, Zr and Hf) for Potential Thermoelectric Applications: Hybrid-DFT Approach

Wed, 01 Jan 2020 00:00:00 GMT

Title: Theoretical Investigation of Lead Perovskite PbXO 3 (X=Ti, Zr and Hf) for Potential Thermoelectric Applications: Hybrid-DFT Approach Authors: Lalhriatzuala

Theoretical Study of ZnS Monolayer Adsorption Behavior for CO and HF Gas Molecules

Sat, 01 Jan 2022 00:00:00 GMT

Title: Theoretical Study of ZnS Monolayer Adsorption Behavior for CO and HF Gas Molecules Authors: Lalhriatzuala Abstract: Adsorption of carbon monoxide (CO) and hydrogen fluoride (HF) gas molecules on a ZnS monolayer with weak van der Waals interactions is studied using the DFT + U method. From our calculation, the ZnS monolayer shows chemisorption with CO (Eads = −0.96 eV) and HF (Eads = −0.86 eV) gas molecules. Bader charge analysis shows that charge transfer is independent of the binding environment. A higher energy barrier for CO when migrating from one optimal site to another suggests that clustering may be avoided by the introduction of multiple CO molecules upon ZnS, while the diffusion energy barrier (DEB) for HF suggests that binding may occur more easily for HF gas upon the ZnS ML. Adsorption of the considered diatomic molecule also results in a significant variation in effective mass and therefore can be used to enhance the carrier mobility of the ZnS ML. Additionally, the calculation of recovery time shows that desirable sensing and desorption performance for CO and HF gas molecules can be achieved at room temperature (300 K).

The effect of mechanical relaxation time in the elastic wave propagation in elastic materials with voids is investigated. The phase speed and the attenuation coefficients are obtained and observed the effect of mechanical relaxation time. The phenomenon of reflection of elastic waves due to the incident waves from a plane boundary of elastic materials with voids is studied. The amplitude and energy ratios of the reflected waves are obtained. Numerically these ratios, phase speeds and the corresponding attenuation coefficients are computed for a particular model and the effect of mechanical relaxation time is discussed.

Sat, 01 Jan 2022 00:00:00 GMT

Title: The effect of mechanical relaxation time in the elastic wave propagation in elastic materials with voids is investigated. The phase speed and the attenuation coefficients are obtained and observed the effect of mechanical relaxation time. The phenomenon of reflection of elastic waves due to the incident waves from a plane boundary of elastic materials with voids is studied. The amplitude and energy ratios of the reflected waves are obtained. Numerically these ratios, phase speeds and the corresponding attenuation coefficients are computed for a particular model and the effect of mechanical relaxation time is discussed. Authors: Lalhriatzuala Abstract: The effect of mechanical relaxation time in the elastic wave propagation in elastic materials with voids is investigated. The phase speed and the attenuation coefficients are obtained and observed the effect of mechanical relaxation time. The phenomenon of reflection of elastic waves due to the incident waves from a plane boundary of elastic materials with voids is studied. The amplitude and energy ratios of the reflected waves are obtained. Numerically these ratios, phase speeds and the corresponding attenuation coefficients are computed for a particular model and the effect of mechanical relaxation time is discussed.