Fabrication and thermoelectric properties of TiFeSb system half-heusler compounds

TiFeSb and Mn-doped (Ti_0.75Mn_0.25)FeSb Half-Heusler compounds as p-type thermoelectric materials were prepared by a solid-state reaction at 850°C, 144 h and followed spark plasma sintering at 800°C under 40 MPa. The X-ray diffraction patterns of the two synthesized materials were tested and calculated based on the first-principles theory for their powder diffraction file can not be found. And their microstructures were characterized and their thermoelectric properties were measured. The results indicate that the experimental XRD patterns of the synthesized TiFeSb and (Ti_0.75Mn_0.25)FeSb match very well with the simulation results. TiFeSb and (Ti_0.75Mn_0.25)FeSb are p-type thermoelectric materials for their Seebeck coefficient values are positive. At 50°C, the ZT value of (Ti_0.75Mn_0.25)FeSb is 4.3 times improved compared with the undoped TiFeSb, because the Mn-doped system improves the conductivity while reduces the thermal conductivity.