Thermoelectric response of ZrNiSn and ZrNiPb Half-Heuslers: Applicability of semi-classical Boltzmann transport theory

Abstract

We investigated the thermoelectric transport mechanism of ZrNiSn and ZrNiPb Half-Heuslers within the Boltzmann transport theory, under constant relaxation time approximation. The prediction of band structure behavior along the high symmetry Brillouin zone and density of states are used to establish relations among various transport coefficients like Seebeck coefficient, electrical conductivity, thermal conductivity and power factor which have been found to be in good agreement with the experimental results. The Seebeck coefficient variation show the n-type behavior of heat carriers. The electrical and thermal conductivity show a semiconducting nature of bands along the Fermi level. The lattice part of thermal conductivity show an exponential decreasing trend along the high temperatures. Power factor variation and figure of merit show the heavier element doping of ZrNiSn results in descent increase in efficiency triggering its applicability. The overall measurements show that semi classical Boltzmann transport theory has well behaved potential in predicting the transport properties of the compounds. Keywords: Boltzmann transport theory, Thermoelectrics, Heusler alloys, Band structure