Dislocations promoted A-site nonstoichiometry and their impacts on the proton transport properties of epitaxial barium zirconate thin films

In the epitaxial barium zirconate (BaZrO3) thin films deposited on NdGaO3 substrates through pulsed laser deposition, the large lattice mismatch between film and substrate can be accommodated by generating a large amount of misfit dislocations at the interface. With careful structural and chemical analyses, an enhancement in barium vacancy concentration together with charge compensating oxygen vacancies is believed to be formed near the dislocation defects, which should be mainly responsible for the great improvement of the proton conductivity. However, the crystallinity deteriorates with increasing film thickness due to the dislocations propagation. Such behavior could lead to a detrimental impact on the proton transport properties. These results could be useful for rational design of coating electrolytes with high proton conductivity by strain engineering for in-plane solid oxide fuel cell applications.