Oxygen pipe diffusion in barium titanate

Determine whether oxygen pipe diffusion along dislocation cores occurs in barium titanate and contributes to oxygen transport during oxidation and reduction processes.

Background

The paper attributes the pronounced oxygen and cation redistribution in oxidized BaTiO₃ to transport along extended defects, particularly the three-dimensional dislocation network in the surface region. Although cation pipe diffusion in perovskites is described as experimentally established, the authors distinguish the unresolved status of oxygen transport along dislocations. Resolving this issue is important for explaining the observed combination of bulk and fast-path oxygen diffusion, the accumulation of ionic charge, and the conductivity changes induced by oxidation and reduction.

The authors perform an ¹⁸O reoxidation experiment and identify diffusion profiles consistent with combined bulk and pipe diffusion, but the broader physical possibility of oxygen pipe diffusion in BaTiO₃ remains unsettled in the cited literature. Establishing whether this mechanism operates would clarify the microscopic origin of the nanoscale segregation and electrical behavior reported in the paper.