Mixing energies of nickel atoms and vacancies in Ni-Te

Abstract

The configurational energy of Ni 1+ x Te 2 is expressed in terms of mixing energies. Using the derived expression the perfectly ordered state is shown to be thermodynamically unstable if the mixing energies given by Coffin et al. were correct. A new Bragg-Williams approximation is derived and used to calculate the mixing energy along the c-direction. The new value is - 1130 K which is very different from + 2300 K obtained previously.