Thermophysical properties of Tl9BiTe6 and TlBiTe2

Polycrystalline samples of Tl9BiTe6 and TlBiTe2 were prepared by melting stoichiometric amounts of component elements in sealed quartz crucibles. At the temperatures of 400-600 K, the heat capacity of TlBiTe2 was measured using an enthalpy method by means of a differential scanning calorimeter (DSC). An empirical equation for the heat capacity C-p of TlBiTe2 was obtained by fitting the experimental data, C-p(J K-1 mol(-1))=79.2+8.27x10(-2)T+1.37x10(5)T(-2). Other thermophysical properties of Tl9BiTe6 and TlBiTe2, viz., melting point, thermal expansion coefficient, elastic moduli, Debye temperature, and thermal diffusivity were also measured, and the relationships between these properties were studied. The measured heat capacity of TlBiTe2 was compared with the estimate one obtained from the Debye temperature, thermal expansion coefficient, and compressibility. The thermal conductivity of TlBiTe2 was evaluated from the thermal diffusivity, heat capacity, and density. (C) 2002 Elsevier Science B.V. All rights reserved.