Structure and conductivity studies of electrodeposited δ-Bi2O3

Bismuth oxide in its δ-phase (high-temperature fluorite structure) is a well-known solid electrolyte owing to its high oxygen ion conductivity. In this work, δ-Bi2O3 thin film was stabilized at room temperature by electrodeposition on different conductor substrates. Electrodeposited thin films have a good quality with an excellent adhesion to the substrate. The crystalline structure and the stability of the deposit were studied by X-ray diffraction (XRD). Both XRD measurements and transmission electron microscopy (TEM) investigation revealed the nanocrystallinity of the films. XRD measurements showed a decrease of nanocrystallites size after thin film annealing. The resistivity measurements showed an excellent conductivity of electrodeposited δ-Bi2O3 thin films with an ionic conductive behaviour and an electrical conductivity value close to the theoretical value: the thin film deposited on a gilded silver substrate exhibit a conductivity of 0.39 S/cm at 440 °C.