Thermodynamic properties of Iron?Tellurium alloys

Abstract

Vapor pressures of tellurium of iron—tellurium alloys were determined between 550 and 900°C and between 0 and 67 at % Te by an isopiestic method. Activities and partial molar enthalpies of tellurium were calculated and integral free energies of formation were obtained by aGibbs-Duhem integration. Two statistical models were used to calculate activities in the hexagonal δ′-NiAs phase. Excellent agreement with the experimental values was obtained by assuming random distribution of iron atoms and iron vacancies in the defected (00 1/2) layers of the lattice. The interaction energy between iron vacancies was found to be 820 cal·g-atom−1.