Enhanced thermoelectric performance of Hf-doped ZrNiSn: a first principle study.

Abstract

In this work, we perform a systematic study on the thermoelectric properties of Zr1-xNiSnHfx using first-principles calculations combined with Boltzmann transport equations. The power factor of Zr1-xNiSnHfx increases as the temperature increases from 300 to 1200K, because the increase in electrical conductivity is greater than the decrease in the Seebeck coefficient. The power factor of Zr7/8NiSnHf1/8 is larger than that of other Zr1-xNiSnHfx thermoelectric materials, but the thermoelectric figure of merit (ZT) is similar to that of others materials. This is due to the higher electronic thermal conductivity of Zr7/8NiSnHf1/8 compared to other materials. The maximum ZT of p-type (n-type) Zr1-xNiSnHfx is 0.98 (0.97), 0.9 (0.89), 0.83 (0.80), and 0.72 (0.73) at 300K, 600K, 900K, and 1200K, respectively, which are greater than those of the pure ZrNiSn. In conclusion, Hf-doped ZrNiSn can enhance the thermoelectric performance and are promising candidates for thermoelectric materials. This paper uses FP-LAPW implemented in the WIEN2K code. The thermoelectric performance is calculated based on the semi-classical Boltzmann theory implanted using the BoltzTraP code. The electronic thermal conductivity (κe) and the carrier concentration (n) have been calculated using the density functional theory.