Microstructure and mechanical properties of doped-lanthanum gallate with addition of yttria-stabilized zirconia

Strontium- and magnesium-doped lanthanum gallate ceramics exhibiting relatively high values of ionic conductivity, and chemical stability over a wide range of oxygen partial pressure are considered potential solid electrolytes for application in electrochemical devices for clean energy production. Recently, the addition of a second phase has been a strategy to improve the performance of solid electrolytes. In this work, doped-lanthanum gallate ceramics with up to 20 wt% yttria-stabilized zirconia addition were investigated to determine the effects of the minor phase on the microstructure evolution, hardness, and elastic modulus of the matrix. Composite solid electrolytes were prepared by mechanical mixing followed by solid-state sintering in the 1350-1500 ℃ range. The mean grain size of composites was lower than that of the matrix for sintering temperatures up to 1400 ℃, but a fast grain growth was observed for higher temperatures. Improved mechanical properties were obtained for composites compared to those of the matrix. (author)