Thermodynamic investigations in the system Bi-Sn-Te

The excess enthalpies of liquid Bi-Te alloys and liquid Bi-Sn-Te alloys were determined in a heat-flow calorimeter. The measurements in the binary system were carried out at 1173 K over the whole range of compositions and for the ternary system along the sections BiySn1-yTe with y = 0.2, 0.5 and 0.8 at 1173 K and with y = 0.5 at 1073 K. The maxima of the exothermic enthalpies in the ternary system are found on a line stretching from Bi2Te3 to SnTe. The association model with additional ternary interaction parameters was applied for the analytical description of the thermodynamic data of the ternary melt. The results of the section Bi0.5Sn0.5-Te were compared with those of the Redlich-Kister formalism applied in the systems Bi-Ge-Te and Bi-Pb-Te. In addition, the phase equilibria of the quasibinary section SnTe-Bi were investigated by DTA and X-ray diffraction measurements. The thermodynamic functions were optimized and the phase diagram of this system was calculated using the experimental data.