Enhanced thermoelectric properties of Hf doped half-Heusler compound NbFeSb

Abstract

The structural, electronic and thermoelectric transport properties of NbFeSb and Nb0.75Hf0.25FeSb have been studied using full potential linearized augmented plane wave (FPLAPW) method as implemented in WIEN2k code and the Boltzmann transport equations. The calculated value of band gap of NbFeSb is 0.53 eV which agrees well with the available data. We have studied the variation of Seebeck coefficient, electrical conductivity, Power factor and electronic thermal conductivity with respect to temperature. The calculated value of electrical conductivity for NbFeSb at room temperature is 0.049×1019 Scm-1sec-1 which increases to value 1.42×1020 Scm-1sec-1 for Nb0.75Hf0.25FeSb. The value of Power factor for pure compound is 2.84×1011 WK-2cm-1sec-1 which also increases to value 3.02×1011 WK−2cm-1sec-1 for Nb0.75Hf0.25FeSb at room temperature. The increase in the value of power factor due to doping suggest that Hf doped NbFeSb can act as efficient thermoelectric material.