Improved oxide ion conductivity of Co doped La0.8Sr0.2Ga0.8Mg0.2O3 perovskite type oxide

Effects of doping certain transition metal cations for the Ga site on the o xide ion conductivity of La0.8Sr0.2Ga0.8Mg0.2O3 has been investigated in de tail. It was found that doping with Co is effective for enhancing the oxide ion conductivity. In particular, a significant increase at low temperature was observed. Electrical conduction can generally be improved by doping tr ansition metal cations, however, the theoretical emf was almost exhibited i n an H-2-O-2 cell utilizing Co doped La0.8Sr0.2Ga0.8Mg0.2O3 for Co concentr ations lower than 10 mol% on the Ga site. Diffusion characteristics of the oxide ion in La0.8Sr0.2Ga0.8Mg0.5Co0.085O3 has also been investigated by us ing the O-18 tracer method. Since the diffusion coefficient measured by the O-18 tracer method is almost the same as that the one estimated via electr ical conductivity measurements, it was concluded that the conduction of La0 .8Sr0.2Ga0.8Mg0.115Co0.085O3 is almost ionic. It seems most likely that the improved oxide ion conductivity by doping with Co is brought about by the enhanced mobility of the oxide ions. (C) 1998 Published by Elsevier Science B.V. All rights reserved.