Cation interdiffusion and anionic conduction in Y2O3-Bi2O3 solid electrolytes

Cation interdiffusion in Y2O3-Bi2O3 solid solutions was examined theoretically and experimentally. It was demonstrated that the interdiffusion coefficient must obey Darken equation and not Nernst-Planck due to high oxygen ion diffusivity. The interdiffusion coefficient was substantially affected by the addition of aliovalent dopants; ZrO2 suppressed while CaO enhanced cation interdiffusion. At the same time, as the majority defects are oxygen vacancies, the ionic conductivity is marginally affected. Suppression of cation interdiffusion kinetically stabilizes the high-conductivity cubic phase without compromising ionic conductivity making these materials excellent candidates a solid electrolytes