Temperature dependence of the figure-of-merit of Ag,,,UsSbo,*,,Teo,,,,

The p-type Ag,,,,Sb,,,,Te,,,, boule was unidirectionally gown using a Bridgman fumace and subsequently rapidly cooled by Ar to form a Wid"nstatten structure of a high temperature phase AgSbTe,, which could be desirable for power generation. Though the boule looked a homogeneous Widmannstatten structure, XRD patterns revealed that some precipitates ofA&Te and Sb,Te, were contained in the boule and increased in volume in the growth direction. The figure-of-merit Z of the p-type Ago,8Sb, 2,1TeoI,, boule have been evaluated in the temperature range From 300 to 700 K. The maximum figure-of-merit 6, was different in the portions ofthe boule. The value of 2.0~ IO-' /K was at 620 K for the former half portion of the boule and that of I .7x IO-' IK was at 585 K for the latter half portion. The AgO,,,Sb,,,ITe,,,, boule with less precipitates showed higher 2 at higher temperatures.