Short‐Circuit Diffusion of Ba, Sr, and O during ATiO 3 (A = Ba, Sr) Thin‐Film Growth by the Hydrothermal–Electrochemical Method

The mass transport mechanism during the hydrothermal‐electrochemical growth of polycrystalline thin films of ATiO 3 (A = Ba, Sr) perovskite onto Ti electrodes in A(OH) 2 solutions has been studied by a tracer technique, using Ba and 18 O atoms as respective tracers for A‐site and oxygen atoms in SrTiO 3 host films. It was found that the ATiO 3 film grows at the film/electrode interface by transport of both A‐site and oxygen atoms from the solution to the interface. A‐site and oxygen atoms are considered to diffuse as constituents of solution species, such as A 2+ , OH ‐ , and H 2 O, through open short‐circuit paths existing at grain boundaries.