Computational investigation of LiMgZ half-heusler phases where Z = P, as, and Bi for optoelectronic and photoelectronic applications
Tahmina Soltana Nashia, Mimsoriya Haque Mim, Md. Tarekuzzaman, Salah Uddin, Omar Alsalmi, Hmoud Al-Dmour, Md. Rasheduzzaman, Md. Shamimul Haque Choudhury, Md. Zahid Hasan
Abstract
This study investigates the structural, electronic, mechanical, elastic anisotropic, optical, and thermodynamic properties of LiMgZ (Z = P, As, Bi) half-Heusler compounds using Density Functional Theory (DFT) as implemented in the Cambridge Serial Total Energy Package (CASTEP). Structural optimization confirms the stability of these compounds in cubic crystalline structures. Detailed analysis of electronic band structures and density of states (DOS) reveals direct band gaps for LiMgP, LiMgAs, and LiMgBi of 1.53 eV, 1.33 eV, and 0.43 eV, respectively, indicating their semiconductor behavior. Mechanical stability and brittleness assessments were performed using computed elastic constants, which satisfy the Born stability criteria. Furthermore, evaluations of elastic moduli indicate that LiMgP and LiMgAs display elastic isotropy, while LiMgBi exhibits notable elastic anisotropy, highlighting its directional dependence in mechanical responses. Important optical properties, including absorption coefficient, dielectric function, electrical conductivity, reflectivity, refractive index, and loss function, were thoroughly examined. The results demonstrated pronounced photoconductive behavior, high optical reflectivity, and suitable dielectric characteristics, suggesting the materials significant potential for applications in microelectronics and optoelectronics devices. Additionally, these compounds exhibit low minimum thermal conductivity ( K min ) and a reduced Debye temperature ( θ D ), making them promising candidates for thermal barrier coating (TBC) applications in advanced thermal management technologies.