Abstract

La_0.9Sr_0.1Ga_0.8Mg_0.2O_{3 − x} (LSGM) has been prepared by a complexing sol–gel process and characterised by X-ray diffraction, thermogravimetric-differential thermal analysis (TG-DTA) and conventional weight analysis. The room-temperature structure is orthorhombic, space group Pnma, with a = 5.5340(14), b = 5.5074(22), c = 7.8003(31) Å. After heating at 1000 °C, the lattice parameters of LSGM shift a little, and La₄SrO₇ and SrLaGaO₄ separate from the parent phase, which may further affect other properties. The weight change of LSGM at 750 °C is insignificant and the phase is also stable after heating at 750 °C in a hydrogen atmosphere for a total of 132 h. Defect chemistry modelling supports the view that LSGM is not single phase at 1000 °C.