The effect of Mg doping on the thermoelectric performance of Zn4Sb3

The effect of Mg doping of Zn₄Sb₃ on thermal and thermoelectric properties has been studied on 4 samples with a doping degree ranging from 0.1 to 2 at.% Mg, and compared to a pure, undoped sample. Laboratory X-ray powder diffraction shows that all samples are pure single phase materials as further evidenced with higher confidence by Rietveld refinement of high resolution synchrotron powder diffraction of the as synthesized 1 at.% and 2 at.% Mg doped samples. Zn₄Sb₃ undergoes a transition from the room temperature disordered beta phase to an ordered alphapsila phase, going over an intermediate alpha phase; differential scanning calorimetry show only small effects of doping on the phase transition temperature. Physical properties have been evaluated from 2-400 K for all samples. Some physical property parameters are affected by doping, but no immediate improvement of ZT was achieved by the doping procedure. The reason for this is discussed in relation to differences in sample compaction.