RELATIONSHIP BETWEEN THERMOELECTRIC PROPE RTIES AND FORMATION OF MICROSTRUCTURE, AND COMPRESSIVE STRENGTH AND GRAIN-SIZE OF BI-TE MATERIALS

Semiconducting ceramics of p- and n-type bismuth telluride fabricated from the milled powders of (Bi2Te3)(0.25)(Sb2Te3)(0.75) + Te 2.0 mass% and (Bi2Te3)(0.95)(Bi2Se3)(0.05) + HgBr2 0.07 mass% with low impurity oxygen having figures of merit were as large as 2.6 x 10(-3) K-1 (p-t ype) and 2.0 x 10(-3) K-1 (n-type) at 25 degrees C, respectively, have been developed by hot press, The figure of merit showed a maximun whe n the grain size was 5 and 10 mu m because thermal conductivity appare ntly became the lowest possibly due to enhanced phonon scattering at g rain boundaries. The compressive strength of p- and n-type obeyed Hall -Petch type which was directly proportional to (-1/2) the power of gra in size, and showed 8.8 and 6.1 MPa whose figure of merit was maximum, respectively.