Effects on the proton conduction limiting barriers and trajectories in BaZr0.875Y0.125O3 due to the presence of other protons

Abstract

Kinetic Monte Carlo (KMC) and graph searches show that proton conduction limiting barriers and trajectories in BaZr0.875 Y0.125 O3 are affected by the presence of other protons. At 1000 K, KMC limiting conduction barriers increase from 0.39 eV to 0.45 eV as the proton number is increased. The proton-proton radial distribution begins to rise at 2 Å and peaks at 4 Å, which is half the distance expected, based on the proton concentration. Density functional theory (DFT) calculations find proton/proton distances of 2.60 and 2.16 Å in the lowest energy two-proton configurations. A simple average of the limiting barriers for 7-10 step periodic long range paths found via graph theory at 1100 K shows an increase in activation barrier from 0.32 eV to 0.37 eV when a proton is added. Both KMC and graph theory show that protons can affect each other's pathways and raise the overall conduction barriers.