Electronical and thermoelectric properties of half-Heusler ZrNiPb under pressure in bulk and nanosheet structures for energy conversion

Abstract

The pressure dependence of structural, electronic and thermoelectric properties of half-Heusler ZrNiPb was investigated in the bulk and nanosheet structures. In order to obtain the accurate results, the full-potential (linearized) augmented plane-wave (FP(L)APW) calculations were performed with the Perdew–Burke–Ernzerhof generalized gradient approximation (PBE-GGA) and modified Becke–Johnson (mBJ) plus spin–orbit coupling (SOC). Obtained band gap values are in close agreement with the experimental results (< 0.5 eV). The variations of the thermoelectric properties of the ZrNiPb were studied under different temperatures, carrier concentrations and the hydrostatic pressures. The results show that the hydrostatic pressure decreases the lattice constant value. The band structure calculations display that the band gap increases with pressure for the bulk state and it is 0 for the nanosheet of ZrNiPb [010]. The highest value of figure of merit (ZT) = 0.95 is found at 9.378 GPa at a carrier concentration of n = 1 × 1018 cm−3 at 250 K for p-type of ZrNiPb.