First-principles calculations to investigate structural, elastic, electronic, thermoelectric, dynamic, and optical properties of BeNaZ (Z = As, Sb, and Bi) Half-Heusler compounds

Abstract

This study examined the structural, elastic, electrical, magnetic, thermoelectric, dynamic, and optical properties of BeNaZ (Z = As, Sb, and Bi) Half-Heusler compounds utilizing ab initio methods. We employed the modified Becke-Johnson (mBJ) exchange–correlation function to enhance understanding of the electronic band gap. The measured band gaps are 1.98, 1.225, and 0.29 eV for BeNaZ (where Z represents As, Sb, and Bi), signifying semiconductor characteristics. The computed elastic constants indicate that these compounds possess mechanical stability. The three examined compounds’ negative formation energy estimates for α phases of the BeNaZ indicate their thermodynamic stability. Positive phonon frequencies suggest the dynamic stability of BeNaZ compounds. We have examined optical properties including the dielectric constant ε(ω), absorption coefficient α(ω), optical conductivity σ(ω), extinction coefficient k(ω), refractive index n(ω), reflectivity R(ω), and energy loss function L(ω). The thermoelectric properties of BeNaZ compounds were examined, revealing that the at room temperature, ZT parameters are 0.25 while 1.05 at 700 K for BeNaAs, which has better transport performance at high temperature, followed by BeNaSb and BeNaBi. These HH compounds demonstrate significant potential for thermoelectric and optoelectric applications.