High Temperature Thermodynamic Properties of ZnTe(s)

Abstract

We have gathered the partial pressure, Knudsen cell, and emf measurements on ZnTe(s) from which the Gibbs energy of formation can be calculated. Published partial pressures of diatomic tellurium have been adjusted to take account of a subsequently published third law analysis of tellurium. The equation used to calculate the total pressure from the rate of mass loss from an extensive set of Knudsen cell measurements has been corrected to give a 5% increase in total pressure and the Gibbs energy of formation has been recalculated. A high temperature heat capacity for ZnTe(s) has been selected from the published data. The Gibbs energies of formation as a function of temperature have then been fit using a third law analysis to give two essentially equally good but extreme fits. In the first, the standard enthalpy of formation agrees with the calorimetric value of −119 kJ/mol but the standard entropy of ZnTe(s) is low by 2-3 J/mol K. In the second, the standard enthalpy of formation is more positive than the calorimetric values by about 3 kJ/mol but the standard entropy of ZnTe(s) is 82 J/mol K and close to the value from low temperature heat capacity measurements. We select values of −119.49 kJ/mol for the standard enthalpy of formation and 78.23 J/mol K for the standard entropy.