Electron microscope images and diffraction patterns have been recorded of several crystalline samples of La1-xSrxGa1-yMgyO3-(x+y)/2 prepared through a novel solution combustion synthesis route. In addition to the sharp Bragg reflexions, diffuse reflexions including some hitherto unreported features indicating the presence of microdomains embedded in the average cubic perovskite matrix were obtained. An attempt has been made to identify the microdomain structure using diffraction evidence from coarsened samples and an analogy with stabilized zirconia has been drawn. (C) 2000 Elsevier Science B.V. All rights reserved.