Kinetic Monte Carlo study of protonic diffusion and conduction in Gd-doped BaCeO3

• We study protonic diffusion and conduction in Gd-doped BaCeO3.
• A first-principle based Kinetic Monte Carlo algorithm is used.
• Gadolinium dopants act like shallow traps without affecting the protonic diffusion.
• Protonic conduction is found to be isotropic.

Protonic diffusion and conduction in Gd-doped BaCeO3 are studied by Kinetic Monte Carlo simulations using transition rates deduced from previous ab initio calculations. The dopants behave like shallow traps for the protonic defects, but at low doping concentrations, their presence does not reduce the diffusion coefficient, and the activation energy (≈ 0.36 eV) is not significantly affected by the doping rate. We tentatively explain this result by the interplay between the creation of traps consecutive to doping, and the removal of obstacles in the primitive protonic energy landscape, keeping in mind that our model neglects the increase in attraction between protons and dopants when the dopant concentration increases. The protonic mobility is computed, under finite applied electric field, and found at ≈ 5.54 × 10− 9 m2·s− 1·V− 1 at 600 K and at 86.1 × 10− 9 m2·s− 1·V− 1 at 1200 K. These first results suggest that protonic conduction in Gd-doped BaCeO3 is rather isotropic.