Dissociation and sublimation of tellurium from the thermoelectric tellurides

Abstract

The authors have recently reported that Te in Pb_{(1 − x)}Sn_xTe (0 ≤ x ≤ 1) system compounds will be dissociated and sublimated at high temperatures over 400°C on the basis of experimental results. In the experiment, the thermal expansion was tested and the thermogravimetry-differential thermal analysis was carried out from the room temperature to 500°C. In the present work, a high-temperature X-ray diffraction profiles are observed to investigate the change in the crystal structure of PbTe and Bi₂Te₃. It is concluded from the experimental results that Te will be dissociated and move onto the sample surface to form a liquid or amorphous state at temperatures ranging from 200 to 400°C and that Te on the sample surface will be volatilised at higher temperatures than 400°C. It is also concluded that in Bi₂Te₃, Te might be sublimated even at lower temperatures than 400°C.

Keywords:

• Thermoelectric material
• PbTe
• SnTe
• Bi₂Te₃
• X-ray diffraction analysis