Eutectoid decompositions in Ce-containing ABO 3 perovskites: Part II, the case of divorced growth in CeCrO 3

A eutectoid phase transformation was exhibited by the perovskite CeCrO when heated in air. The kinetics of the reaction, microstructure of the product, and mechanisms of the transformation were studied using thermogravimetric analysis, X-ray and Raman spectroscopy, X-ray diffraction, and electron microscopy. Fluorite CeO and corundum Cr O were formed from the decomposition of CeCrO . The CeO particles were porous and polycrystalline, a consequence of nucleation, growth, and impingent of CeO domains on the CeCrO particles. Anisotropic growth is indicated by the morphology of the CeO grains, while the Cr O particles were single crystals without any crystallographic orientation relationship to the parent phase. Unlike the CeAlO eutectoid, the microstructure comprised of CeO and Cr O show no characteristics of a microstructure formed by cooperative growth. The disparity between the eutectoid reactions in CeCrO and CeAlO is attributed to a difference in interfacial energy between the fluorite and sesquioxide phases (i.e., CeO /Al O versus CeO /Cr O ).