Preparation and Characteristics of Bi 0.5 Na 0.5 TiO 3 Single‐Crystalline Films by a Solid‐State Process

A novel process was demonstrated for the preparation of an epitaxial Bi 0.5 Na 0.5 TiO 3 (BNT) single‐crystalline film on a SrTiO 3 single crystal substrate by simply heating a composite consisting of a BNT powder layer on the substrate. The BNT powder layer was formed on the substrate by spin coating and the composite was heated at 1150°C for several hours in a lidded crucible containing the BNT powder to avoid evaporation of Na and Bi from the composite. This yielded an epitaxial BNT single‐crystalline film several micrometers thick. The film had a high degree of orientation with the rocking curve full width at half maximum of 0.064°. The mechanism of film formation was found to be solid‐state spreading of BNT powder particles on the substrate, and a dense film was obtained from the porous powder layer.