Electronic and elastic properties of BaLiF 3 with pressure effects: First-principles study

132

Using first‐principles calculations, the structural, elastic, and electronic properties of MoAlB have been investigated. The optimized lattice constants exhibit fair agreement with the experimental results. The computed elastic constants satisfy the mechanical stability conditions for MoAlB. The Mo‐based boride MoAlB is elastically anisotropic and classified as brittle material. This boride is expected to be thermally conductive due to its high Debye temperature of 693 K. The metallic conductivity of this compound is predicted by means of electronic structure calculations. The chemical bonding in MoAlB is basically covalent that is assured with the results of DOS, Mulliken population, and charge density distribution. The hardness value of 11.6 GPa for MoAlB suggests that it is relatively soft compared to many others borides. The Fermi surface is formed due to low dispersive Mo 4d‐like bands, which makes the compound a conductive one.

Section: Resultsmentioning

confidence: 99%

Theoretical investigation of structural, elastic, and electronic properties of ternary boride MoAlB

Ali¹,

Hadi²,

Hossain³

et al. 2017

132

“…Solids are easy to crack if they have a large elastic anisotropy. Elastic anisotropy of a solid can be directly illustrated by its directional Young's modulus, which for cubic crystals is defined as follows :

E = 1 ∖ [S_{11} - β (n_{1}^{2} n_{2}^{2} + n_{1}^{2} n_{3}^{2} + n_{2}^{2} n_{3}^{2})],

where

β = 2 S_{11} - 2 S_{12} - S_{44}

and ( n 1 , n 2 , n 3 ) are the direction cosines.…”

Section: Resultsmentioning

confidence: 99%

Electronic, elastic, lattice dynamic and thermal conductivity properties of Na₃OBr via first principles

Cui

Wang

et al. 2017

Self Cite

Na3OBr is expected to be a promising superionic conductor for use as solid state electrolyte in large scale energy storage systems, but its lattice dynamic and thermal conductivity properties have not been well studied till now. In this work, we performed a detailed study on these properties as well as its electronic and elastic properties using first principles method. The results indicate that Na3OBr is a direct band gap crystal. It is mechanically stable but elastically anisotropic. Its phonons at the Brillouin zone center were classified using group theory analysis and its Born effective charges, LO–TO splitting, and dielectric constants were calculated and discussed. Its phonon dispersion curves were obtained and their origins were revealed. Based on the phonon dispersion curves, its thermal conductivity as a function of temperature was predicted, which give a value of 7.30 Wm−1 K−1 at 300 K. Further study reveals that, for Na3OBr, the simple Slack's model can give almost the same thermal conductivity curve as that obtained from the phonon dispersion curves.

“…In this method, a set of specific homogeneous deformations (strains) of a predetermined value is applied and after that the resulting stress is calculated with regard to optimizing the internal degrees of freedom. The elastic properties of many materials together with metallic systems are calculated successfully using this method. The elastic constants are evaluated from the stress tensor σ ij under a set of applied strain δ j via the equation

σ_{i j} = \underset{i j}{true \sum} C_{i j} δ_{j} .

…”

Section: Methodsmentioning

confidence: 99%

First‐Principles Study of Superconducting ScRhP and ScIrP pnictides

Nasir

Hadi

Rayhan

et al. 2017

For the first time, we have reported in this study an ab initio investigation on elastic properties, Debye temperature, Mulliken population, Vickers hardness, and charge density of the two recently synthesized superconducting ScRhP and ScIrP pnictides. The optimized cell parameters show fair agreement with the experimental results. The mechanical stability of both ternary phosphides is confirmed via the calculated elastic constants. Both compounds are ductile in nature and damage tolerant. ScIrP is expected to be elastically more anisotropic than ScRhP. The estimated value of Debye temperature predicts that ScRhP is thermally more conductive than ScIrP and the phonon frequency in ScRhP is higher than that in ScIrP. Both pnictides are soft and easily machinable due to their low Vickers hardness. Moreover, the hardness of ScRhP is lower due to the presence of antibonding Rh–Rh in ScRhP. The metallic conductivity of ScRhP reduces significantly when Rh is replaced with Ir. The main contribution to the total density of states (TDOS) at Fermi‐level (EF) comes from d‐electrons of Sc and Rh/Ir in both pnictides. These two ternary compounds are characterized mainly by metallic and covalent bonding with little ionic contribution. The calculated superconducting transition temperatures fairly coincide with the reported measured values.