Thermoelectric Properties of Mn-Doped FeVSb Half-Heusler System Synthesized via Mechanical Alloying

Abstract

Mn-doped FeVSb half-Heusler alloys were synthesized via a mechanical alloying process and consolidated by vacuum hot pressing. The microstructure and phase transformation of all the samples were examined by XRD and SEM. Thermoelectric properties such as the Seebeck coefficient, electrical conductivity and thermal conductivity were investigated in the moderate temperature range from 300 to 973 K. The negative value of both the Seebeck and Hall coefficients confirms the presence of n-type conductivity. The Seebeck coefficient increased with an increasing doping amount, but the electrical conductivity decreased, owing to decreasing carrier concentration. The thermal conductivity found in this experiment was quite high, possibly due to bipolar diffusion of the electronic band energy. The maximum value of the dimensionless figure of merit was achieved using a relatively high value of the Seebeck coefficient and a significantly higher value of electrical conductivity. The maximum value of ZT was observed for Fe0.996Mn0.004VSb at 468 K.