Publications

Density functional analysis of fluorite-structured (Ce, Zr)O₂/CeO₂ interfaces [Density functional analysis of fluorite-structured (Ce, Zr)O₂/CeO₂ interfaces: Implications for catalysis and energy applications]

Weck, Philippe F.; Juan, Pierre-Alexandre J.; Dingreville, Remi P.; Kim, Eunja K.

The structures and properties of Ce_1–xZr_xO₂ (x = 0–1) solid solutions, selected Ce_1–xZr_xO₂ surfaces, and Ce_1–xZr_xO₂/CeO₂ 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)O₂ phases, indicating a significant rise in microhardness from CeO₂ to ZrO₂, without appreciable loss in ductility as the interfacial stoichiometry changes. Surface energy calculations for the low-index CeO₂(111) and (110) surfaces show limited sensitivity to strong 4f-electron correlation. The fracture energy of Ce_1–xZr_xO₂(111)/CeO₂(111) increases markedly with Zr content, with a significant decrease in energy for thicker Ce_1–xZr_xO₂ films. These findings suggest the crucial role of Zr acting as a binder at the Ce_1–xZr_xO₂/CeO₂ interfaces, due to the more covalent character of Zr–O bonds compared to Ce–O. Finally, the impact of surface relaxation upon interface cracking was assessed and found to reach a maximum for Ce_0.25Zr_0.75O₂/CeO₂ interfaces.