Thermoelectric properties of p-type Bi-Sb-Te crystals with a composite structure

Abstract

The p-type Bi-Sb-Te compounds are most useful for electric cooling devices at room temperature. When Bi-Sb-Te system is Te-rich, lamellar precipitates can be formed according to the Sb-Te phase diagram. How the precipitates affect the thermoelectric properties of Bi-Sb-Te crystals has been investigated in this paper. The Bi-Sb-Te crystals containing some precipitates were obtained from the Te-rich Bi-Sb-Te boules grown by Bridgeman method. The thermoelectric properties of the crystals were changed with the composition and the crystal growth rate. When the composition was (Bi/sub 0.21/Sb/sub 0.79/)/sub 2/Te/sub 3.15/ and also the growth rate was 7.2 mm/h, the figure of merit was highest. The precipitates consisted of Te and Bi-Sb-Te lamellas.