Orientation-controlled phase transformation of Bi2O3 during oxidation of electrodeposited Bi film

High-temperature fluorite structure Bi2O3 is a well-known solid electrolyte owing to its high oxygen ion conductivity. In this study, Bi2O3 thin film was prepared by the oxidation process of the electrodeposited metallic Bi film. The crystal structures of the oxidized Bi films varied with the applied voltages during the electroplating process. Pure α-Bi2O3 was obtained when the oxidation was conducted for the metallic Bi film electrodeposited at −0.1 V. Only β-Bi2O3 was observed as a −0.5 V electrodeposited Bi film was oxidized. The crystal structure of Bi2O3 obtained by oxidation of metallic Bi film may dominantly be affected by the orientation of as-electrodeposited Bi film. Such kind of process is favorable to the preparation of functional ceramic with specific crystal structure.