It was found that doping with Ni improved the oxide-ion conductivity of La0.8Sr0.2Ga0.8Mg0.2O3-based perovskite oxides. Taking account of the ionic transport number and the electrical conductivity, the optimum composition of Ni-doped samples was found to be La0.8Sr0.2Ga0.8Mg0.13Ni0.07O3. In this composition, the electrical conductivity was essentially  independent  of the O  partial pressures ranging from 1 to 10-21atm. Consequently, oxide-ion conductivity still predominated in the optimized composition.

Oxide Ion Conductivity in La0.8Sr0.2Ga0.8Mg0.2-xNixO3 Perovskite Oxide and Application for the Electrolyte of Solid Oxide Fuel Cells. T.Ishihara, T.Shibayama, H.Nishiguchi, Y.Takita: Journal of Materials Science, 2001, 36[5], 1125-31