Preparation and evaluation of PbTe-FGM by joining melt-grown materials

The 2-stage functionally graded materials (FGM) of carrier concentration controlled PbTe were prepared by plasma activated sintering (PAS) using the discs cut from melt-grown PbTe ingots. The component materials of PbTe ingots were prepared by the Bridgman method with 2000 or 4000 molppm PbI/sub 2/ as a n-type dopant. The thermoelectric characterization of the FGM was made in the temperature range from 300 to 700 K. The thermoelectric power (/spl alpha/) and the electrical conductivity (/spl sigma/) for the FGM was almost intermediate between those for the components. In the measured temperature range, the power factor (/spl alpha//sup 2//spl sigma/) value for the FGM was found to exceed that for the components. This results indicate the possibility to realize high efficiency of energy conversion with the well designed FGM structure.