Johnston-Peck Aaron C, Biacchi Adam J, Maier Russell A
Material Measurement Laboratory National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 United States.
Physical Measurement Laboratory National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, MD 20899 United States.
J Am Ceram Soc. 2024 Jul;107(7). doi: 10.1111/jace.19773.
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 CrO 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 CrO particles were single crystals without any crystallographic orientation relationship to the parent phase. Unlike the CeAlO eutectoid, the microstructure comprised of CeO and CrO 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/AlO versus CeO/CrO).
钙钛矿型CeCrO在空气中加热时会发生共析相变。利用热重分析、X射线和拉曼光谱、X射线衍射以及电子显微镜研究了该反应的动力学、产物的微观结构以及相变机制。CeCrO分解生成萤石型CeO和刚玉型CrO。CeO颗粒为多孔多晶结构，这是CeO畴在CeCrO颗粒上形核、生长和碰撞的结果。CeO晶粒的形态表明其生长具有各向异性，而CrO颗粒为单晶，与母相不存在任何晶体学取向关系。与CeAlO共析不同，由CeO和CrO组成的微观结构没有协同生长形成的微观结构特征。CeCrO和CeAlO中共析反应的差异归因于萤石相和三氧化物相之间界面能的差异（即CeO/AlO与CeO/CrO）。
