Structural stabilization and ionic conductivity of bismuth niobium oxide films with fluorite-like structure

Abstract

High ionic conductivity Nb-doped fluorite-like δ-Bi2O3 films were produced using confocal magnetron sputtering. The structural stability of the films was evaluated by high-temperature X-ray diffraction showing that the films were stable up to 400 °C. The ionic contribution to the total electrical conductivity was demonstrated since the AC-conductivities were three orders of magnitude larger than DC-values. The un-doped δ-Bi2O3 film presents high ionic conductivity, but it is lost above 200 °C due to structural changes. Meanwhile, the 5.1 at.% of Nb presented ionic conductivity (2.7 × 10−2 S cm−1) larger than other ionic conductors and was stable from room temperature to 400 °C.