Mechanical alloying followed by subsequent vacuum hot pressing was utilized for the synthesis of Fe_1-xMn_xVSb (0.01 £ x £ 0.05) half-Heusler alloys. Controlling doping concentration could make a major effect on thermoelectric properties of this system. Near single half-Heusler phases were found to be dominating in all the samples, however, a fraction of second phases also traced. Investigation of microstructure revealed that ultrafine microstructure was formed in vacuum hot pressed samples. Thermoelectric properties were studied as a function of doping concentration and temperature. The absolute value of Seebeck coefficient was found to be increased with increasing temperature and doping concentration. Electrical conductivity was found to be decreased slightly with increasing temperature. Thermal conductivity and lattice thermal conductivity decreased considerably with increasing temperature, which could be due to increasing effective mass, grain boundary scattering, second phase interaction, and substitutional defect. The resultant maximum thermoelectric figure of merit was found to be 0.21 for x = 0.03 at 567 K. No incorporation of foreign elements was found during handling and processing.

Keywords: Doping, Seebeck Coefficient, Thermal Conductivity, Half-Heusler