First-principles investigation on the phase stability and chemical bonding of phase-change random alloys

The phase stability and bond character of m InSb ⋅ n InTe ( m = 1 , n = 2 or 3) phase-change materials have been investigated by means of ab initio calculations. The results show that In3SbTe2 (IST312) is a metastable phase and is less stable than In4Sb1Te3 (IST413). IST312 will decompose into InSb and InTe as analyzed by formation energies. The chemical bonding in IST312 is rather inhomogeneous, i.e. strong and weak In–Sb or In–Te bonded pairs observed in IST312, which is similar to the available phase-change materials and may lead to its easy phase-change. While in IST413, the bond strengths of In–Sb or In–Te are identical. The present results will provide a fundamental understanding on the phase stability and chemical bonding of m InSb ⋅ n InTe ( m = 1 , n = 2 or 3) alloys and may be applied to develop new InSbTe based phase-change materials.