Prediction of new stable crystal structures for ternary ErAgTe2 and YAgTe2 semiconductors: Ab initio study

The crystal structure, electronic, mechanical, and phonon properties of rare-earth ErAgTe2 and YAgTe2 compounds have been investigated using first-principles calculations based on density functional theory. We consider three different crystal structures: tetragonal (space group P 4 21m, No. 113), orthorhombic (space group P212121, No. 19), and trigonal (space group P3m1, No. 156). The results indicate that all structures exhibit mechanical and dynamical stability with an anisotropic and ductile nature. The band gap is calculated using both PBE and HSE06 methods. The electronic properties of ErAgTe2 and YAgTe2 revealing the energy band gaps indicate that these compounds are semiconductors. The mechanical properties such as bulk, shear, Young's modulus, and Poisson's ratio were calculated. Finally, we explored the thermodynamic parameters, including the Debye temperatures and minimum thermal conductivities.