Pb1-xMnx crystals as a new thermoelectric material

We studied experimentally properties of p-type bulk crystals of Pb1-xMnTe and Pb1-x-yAgyMnxTe (0≤x≤).083 and y≤0.017) at room and liquid nitrogen temperatures. Model calculations of the thermoelectric figure of merit parameter (Z) involved the analysis of carrier concentration, carrier mobility, density of states as well as electronic and lattice contributions to the thermal conductivity of PbMnTe. In the analysis we took into account the main effect of Mn concentration and the band structure parameters of PbMnTe, i.e. the increase of energy gap. The analysis of electrical, thermoelectric, and thermal properties of Pb1-xMnxTe crystals showed that, at room temperature, the maximum values of the parameter Z occur in crystals with Mn content 0.05≤x≤0.07 and are comparable with a maximal value of Z observed in PbTe. At T = 400 K the increase in the parameter Z by 10% is expected in Pb1-xMnxTe crystal (as compared to PbTe) for a very high concentration of holes about p = 5x1019 Cm-3. The experimental data correctly reproduce the theoretical Z(p) dependence. (author)