Molecular Dynamics Approach to the Physical Mixture of In₂O₃ and ZrO₂: Defect Formation and Ionic Diffusion

Recent research on the use of physical mixtures In₂O₃-ZrO₂ has raised interesting questions as to how their combination enhances catalytic activity and selectivity. Specifically, the relationship between oxygen diffusion and defect formation and the epitaxial tension in the mixture should be further investigated. In this study, we aim to clarify some of these relationships through a molecular dynamics approach. Various potentials for the two oxides are compared and selected to describe the physical mixture of In₂O₃ and ZrO₂. Different configurations of each single crystal and their physical mixture are simulated, and oxygen defect formation and diffusion are measured and compared. Significant oxygen defect formation is found in both crystals. In₂O₃ seems to be stabilized by the mixture, while ZrO₂ is destabilized. Similar results were found for the ZrO₂ doping with In and ln₂O₃ doping with Zr. The results explain the high activity and selectivity catalyst activity of the mixture for the production of isobutylene from ethanol.