抄録
Homogeneous Pb1-xSnxTe crystals with x=0.10, 0.15, 0.25, 0.50 were successfully grown by a new method in that the furnace was being rocked during cooling down under a unidirectional temperature gradient as well as melting. Thermoelectric properties at room temperature were examined as a function of x. They were analyzed on the basis of the Kane model. It was found that reduced the Fermi energy and the effective mass were Proportional to x up to 0.25. Temperature dependence of the thermal conductivity was calculated from the measured value of thermal conductivity at room temperature, approximating that the lattice thermal conductivity is proportional to T-1. Temperature dependence of the figure-of-merit was estimated from the calculated value of thermal conductivity and the measured ones of resistivity and thermoelectric power. From these results, the optimum combination of Pb1-xSnxTe crystals for power generation were determined for the temperature range from 300 to 800K. The combination was x=0.15, 0.25 and 0.50 forming 3-step FGM. The maximum energy conversion efficiency was 27% larger than that of the homogeneous Pb0.50Sn0.50Te. It was also confirmed that sufficient FGM effects on power generation can be realized even by 2-step FGM.
