Ab initio based interionic interactions in calcium aluminotitanate oxide melts: structure and diffusion

Abstract

Calcium aluminotitanate (CaO–Al2O3–TiO2) ternary oxides are of fundamental interest in Materials as well as Earth and environmental science, and a key system for several industrial applications. As their properties at the atomic scale are scarcely known, interionic interactions for the melts are built from a bottom up strategy consisting in fitting first only Al2O3, CaO and TiO2 single oxide compounds separately with a unified description of the oxygen charge and O–O interaction term. For this purpose, a mean-square difference minimization of the partial pair-correlation functions with respect to the ab initio reference was performed. The potentials for the ternary oxide are finally built straightforwardly by adding purely Coulomb terms for dissimilar cation–cation interactions without further fit. This general and unified approach is transferable and successfully describes the structural and diffusion properties of the three single oxides as well as the ternary melts simultaneously. A possible underlying structural mechanism at the origin of the diffusion evolution with TiO2 content is proposed based on the formation of Ti induced triply bonded oxygen.