Density Functional Analysis of Fluorite-Structured (Ce, Zr)O 2 /CeO 2 Interfaces

This is the authors' abstract. We don't add key points for this paper.

The structures and properties of Ce 1– x Zr x O 2 ( x = 0–1) solid solutions, selected Ce 1– x Zr x O 2 surfaces, and Ce 1– x Zr x O 2 /CeO 2 interfaces were computed within the framework of density functional theory corrected for strong electron correlation (DFT+ U ). The calculated Debye temperature increases steadily with Zr content in (Ce, Zr)O 2 phases, indicating a significant rise in microhardness from CeO 2 to ZrO 2, without appreciable loss in ductility as the interfacial stoichiometry changes. Surface energy calculations for the low-index CeO 2 (111) and (110) surfaces show limited sensitivity to strong 4f-electron correlation. The fracture energy of Ce 1– x Zr x O 2 (111)/CeO 2 (111) increases markedly with Zr content, with a significant decrease in energy for thicker Ce 1– x Zr x O 2 films. These findings suggest the crucial role of Zr acting as a binder at the Ce 1– x Zr x O 2 /CeO 2 interfaces, due to the more covalent character of Zr–O bonds compared to Ce–O. The impact of surface relaxation upon interface cracking was assessed and found to reach a maximum for Ce 0.25 Zr 0.75 O 2 /CeO 2 interfaces.