Stabilizing nanocrystalline grains in ceramic-oxides

Abstract

Nanocrystalline ceramic-oxides are prone to grain growth rendering their highly attractive properties practically unusable. Using atomistic simulations of ceria as a model material system, we elucidate a framework to design dopant-pinned grain boundaries that prevent this grain growth. While in metallic systems it has been shown that a large mismatch between host and dopant atomic sizes prevents grain growth, in ceramic-oxides we find that this concept is not applicable. Instead, we find that dopant–oxygen vacancy interaction, i.e., dopant migration energy in the presence of an oxygen vacancy, and dopant–oxygen vacancy binding energy are the controlling factors in grain growth. Our prediction agrees with and explains previous experimental observations.