First-principles insight on elastic, electronic, and thermoelectric transport properties of BAgX (X = Ti, Zr, Hf)

Abstract

The geometrical structures of BAgX (X = Ti, Zr, Hf) are relaxed and their dynamical stability is confirmed by phonon dispersion curves, based on the first-principles density functional theory. Band energy structures, effective masses, relaxation time and carrier mobility of these structures are also obtained. The elastic constants and the deformation potential constants of each structure are calculated with the deformation potential theory. The lattice thermal conductivity is calculated by employing the Slack equation and elastic matrix. The electronic thermal conductivity, Seebeck coefficient, and power factors are obtained by solving the Boltzmann equation. Finally, the dimensionless figure of merit (ZT) is evaluated. The results demonstrate that a maximum ZT value of 0.8–1.2 could be achieved for the n-type BAgX, and the largest one is 1.2 for the n-type BAgZr at the carrier concentration value of 1.17 × 1020 with the temperature of 500 K, implying that the n-type BAgZr is a promising candidate for thermoelectric materials. Keywords: Dimensionless figure of merit, Lattice thermal conductivity, Elastic, Thermoelectric properties, First-principles