Modifying the barriers for oxygen-vacancy migration in fluorite-structured CeO_2 electrolytes through strain: a computer simulation study

摘要

Static lattice simulation techniques were used to examine the effect of strain on oxygen-vacancy migration in the fluorite-structured oxygen-ion conducting electrolyte CeO_2. Activation energies for vacancy migration, △E_(mig), were calculated as a function of isotropic and biaxial strain. In both cases, significant modification of the energetic barriers for oxygen-vacancy migration was found. Analysis of the data yields the activation volumes, △V_(mig), and activation enthalpies, △H_(mig). Simple comparisons based on the calculated data suggest that a biaxial, tensile strain of 4% may increase the in-plane conductivity at T = 500 K by close to four orders of magnitude. Enhancement of the oxygen-ion conductivity of an oxide heterostructure through space-charge effects is also discussed.