Methods for forming a metal oxide electrolyte improve ionic conductivity. Some of those methods involve applying a first metal compound to a substrate, converting that metal compound to a metal oxide, applying a different metal compound to the metal oxide, and converting the different metal compound to form a second metal oxide. Electrolytes so formed can be used in solid oxide fuel cells, electrolyzers, and sensors, among other applications.
STATEMENT REGARDING FEDERALLY-SPONSORED RESEARCH AND DEVELOPMENT
 This invention was made with government support awarded by the Department of Energy and administered by Oak Ridge National Laboratory/UT Battelle. The government has certain rights in the invention.