The microstructure and conductivity of La0.8Sr0.2Ga0.9+xMg0.1O3, where x ranged from -0.02 to 0.04, were studied as a function of the Ga content. Depending upon the heat treatment and the Ga content, various compounds (Ga3LaSrO7, LaSrGaO4, La2O3) were identified in addition to the perovskite phase. Dilatometric measurements showed that a volume expansion occurred, at 1300 to 1500C, which decreased from x = -0.02 to x = 0.04. This appeared to be due to the amount of the LaSrGaO4 second phase which was present. The ionic conductivity decreased with increasing Ga content. This was attributed to a reduction in the O vacancy concentration and to formation of the insulating Ga3LaSrO7 phase.

Material Properties of La0.8Sr0.2Ga0.9Mg0.1O3 as a Function of Ga Content. A.Ahmad-Khanlou, F.Tietz, D.Stover: Solid State Ionics, 2000, 135[1-4], 543-7