High thermoelectric performance of topological half-Heusler compound LaPtBi achieved by hydrostatic pressure

Abstract

The topological phase transition and thermoelectric performance of LaPtBi under hydrostatic pressure up to 34.6 GPa have been systematically investigated using first-principles calculations based on density functional theory. The results indicate that the band structure can be tuned by applying hydrostatic pressure. As the energy band gap is opened under the hydrostatic pressure, a topological phase transition occurs in this material, changing from a topologically nontrivial semimetal to a trivial semiconductor. In addition, the hydrostatic pressure also has a remarkable effect on the thermoelectric properties of the topological half-Heusler compound LaPtBi. Though the lattice thermal conductivity shows a continuous increase with increasing hydrostatic pressure, the power factor is greatly enhanced due to the increase of the Seebeck coefficient. As a result, a maximum ZT value of 1.74 at 1000 K is achieved in n-type LaPtBi under pressure of 21.0 GPa. It is obvious that the thermoelectric figure of merit of LaPtBi is far beyond that of state-of-the-art half-Heusler thermoelectric materials, such as ZrNiSn, FeNbSb and TiCoSb. The realization of high thermoelectric performance in the half-Heusler compound LaPtBi under hydrostatic pressure could provide a new way to further explore other topological thermoelectric materials.