Thermoelectric transport properties of metal phosphide XLiP (X = Sr,Ba)

Abstract

Metal phosphides are stable and have excellent electrical characteristics, their high thermal conductivity has prevented them from being used as thermoelectric materials. In this paper, the thermoelectric transport properties of XLiP (X=Sr,Ba) are investigated on the basis of first-principles calculations, Boltzmann transport equation (BTE) and self-consistent phonon theory (SCP). In addition, we also consider the effect of quartic anharmonicity on the thermal transport properties and lattice dynamics of SrLiP and BaLiP. The strong anharmonicity of the two compounds make the lattice thermal conductivity decrease rapidly with the increase of temperature. At 300 K, the lattice thermal conductivity of SrLiP and BaLiP on the a(b)-axis is only 2.98 and 2.93 Wm$^{-1}$K$^{-1}$, respectively. Due to its excellent electron transport properties, it has greater conductivity in the a(b) axis. Finally, due to the energy pocket and anisotropy at the bottom of the conduction band, the n-type maximum ZT values of trapped SrLiP and BaLiP on the a(b) axis are 0.87 and 0.94 at 900 K, respectively. The high thermoelectric performance of both compounds encourages further studies on the thermoelectric (TE) properties of metal phosphides.

Strong anharmonicity and medium-temperature thermoelectric efficiency in antiperovskite Ca3XN (X = P, As, Sb, Bi) compounds

“…The lattice thermal conductivities were calculated within a 20 × 20 × 20 q -mesh by solving the BTE (eqn (1)), which has been proven to provide sufficient accuracy for a ternary system 34,71 and has been tested systematically in previous work, 57,72 with the relaxation time evaluated based on four-phonon scattering, 73 which iswhere N is the number of q points, c q , s is the phonon mode heat capacity and v i q , s is the group velocity of phonon mode ( q , s ) in the i direction, and τ q is the relaxation time.…”

“…The lattice thermal conductivities were calculated within a 20 × 20 × 20 q-mesh by solving the BTE (eqn (1)), which has been proven to provide sufficient accuracy for a ternary system 34,71 and has been tested systematically in previous work, 57,72 with the relaxation time evaluated based on four-phonon scattering, 73 which is…”