Sintering of Sol-Gel-Prepared Submicrometer Particles Studied by Transmission Electron Microscopy

We studied the sintering process of sol-gel-prepared monodisperse submicrometer CeO2 spheres by examining the microstructural changes of single spherical particles after successive heat treatment in oxygen up to 850°C using transmission electron microscopy. Steps of organic phase removal, CeO2 crystallization, grain growth, and particle condensation were clearly illustrated. Grain-size and sphere-diameter changes were measured quantitatively using this technique. CeO2 particles were found to be highly porous until collapse, which occurred at~850°C.