First-principles analysis of the physical properties of XAcTe2 (X = Li, Na) Heusler alloys for optoelectronic and thermoelectric devices

Abstract

Materials with diverse properties are in high demand due to their utilization in multipurpose devices. The current work presents the systematical analysis of electronic structure, mechanical, optoelectronic and transport properties of new Heusler XAcTe2 (X = Li, Na) alloys. Density functional theory (DFT) based calculations are carried out first time to compute the physical properties of the alloys. The exchange–correlation potential is solved with modified Becke-Johnson (mBJ) approximation. Structural stability is obtained with ground state optimized lattice parameters, negative formation energy values, and phonon dispersion curves. A brittle nature with an anisotropic character is observed for both alloys. The band structures show a direct bandgap for both alloys, which is also reflected in the density of states. The evaluated optoelectronic response shows the high absorption in the ultraviolet region, confirming their ability to use them in optoelectronic devices. The analysis of thermoelectric parameters shows the high electrical and minimum thermal conductivities for both alloys. The electronic and lattice vibrations dependent high ZT values are achieved for LiAcTe2 and NaAcTe2 alloys. The optoelectronic and thermoelectric responses of the alloys show that they could be promising candidates for use in optoelectronic and renewable energy applications.