Insight into the structural, elastic, lattice dynamical, optical, and thermoelectric properties of novel Heusler alloy LiCaBi by first-principles approach

Abstract

In the current paper, we have explored the structural, mechanical, vibrational, optical as well as thermoelectric characteristics of LiCaBi half Heusler (HH) alloy employing first-principles computations as well as Boltzmann transport theory. The generalised gradient approximation with Perdew Burke-Ernzerhof method (PBE-GGA), TB-mBJ as well as mBJ + SOC exchange potential are used to include the exchange-correlation effect. The TB-mBJ method reveals that the explored alloy possesses a direct energy gap of 2.01 eV. Three elastic constants are utilized to compute other coefficient of elasticity like Young's modulus, shear modulus, bulk modulus, and mechanical properties such as Pugh's ratio, Poisson's ratio, anisotropic factor etc. The brittle/ductile as well as isotropic/anisotropic behaviour of LiCaBi has been investigated in relation to these mechanical properties. In the framework of Debye temperature calculations, various areas of vibrational modes in LiCaBi are also investigated. Owing to their vibrational properties, the compound retains structural dynamic stability. In addition, the analysis of the optical characteristics of this LiCaBi compound in the presence of photon energy radiation demonstrated that this compound has the potential to be a possible candidate for application in optoelectronic devices and solar cell applications. Here the effect of temperature and chemical potential on the thermoelectric transport parameters such as the Seebeck coefficient, electrical conductivity, thermal conductivity, and power factor has been studied comprehensively. The values of power factor conductivity are obtained to be 1.34 × 1012WK−2 at T = 1200 K. The evaluated value of figure of merit ZT is 0.75 at T = 1200 K, proposing high-temperature that LiCaBi may be used as an active thermoelectric alloy in the field of high temperature applications.