P-T-X phase equilibrium in the Zn-Te system

Abstract

P-T-X data are the thermodynamic basis for modeling the crystal growth of materials with controlled stoichiometry. In this paper results of the first direct experimental measurement of the total vapor pressure are reported for three-phase equilibria SLV (solid-liquid-vapor) and VLS (vapor-liquid-solid) in Zn-Te, and the P-T projection of the P-T-X phase diagram is constructed. Geometrical analysis of the phase equilibrium showed that three congruent processes are observed in the Zn-Te system: congruent melting (S = L), sublimation (S = V), and vaporization (L = V). All three congruent curves are tangent to SLV. Consequently, all three congruent points are on the Te-side of the maximum melting point of ZnTe. The vapor pressure scanning method was applied to determine the maximum non-stoichiometry as a function of the temperature. The solidus volume of ZnTe was shown to be on the Te-side of the stoichiometric plane.