Cerium Oxalate Morphotypes: Synthesis and Conversion\ninto Nanocrystalline Oxide

Abstract

Cerium\ndioxide is a scientifically and technologically important\nmaterial with a wide range of potential applications, particularly\nin solid oxide fuel cells and catalysis. Herein, we report a study\nfocusing on the synthesis of nanocrystalline cerium dioxide via thermal\ndecomposition of the oxalate salt. Simply by changing reaction conditions\n(temperature, concentration, acidity, strike) during the precipitation\nof the cerium solution with oxalic acid, we were able to obtain different\nmorphologies. The main reaction parameters were mapped and linked\nto the morphology of the final products. Additionally, it was proved\nthat oxalate precipitation is a robust reaction proceeding at relatively\nextreme contitions. Moreover, the conversion of cerium oxalate to\nnanocrystalline oxide was followed to monitor the progress of the\nreaction, the texture evolution, and the grain growth. The results\nshowed that, for unvaried heating cycle, the grain size of converted\nmaterial is linked to morphology. The thinner was the original microcrystal\nthe smaller were the CeO₂ nanocrystals after calcination.\nIn addition, the grains were found smaller near the edges of the ex-oxalate\nmicrocrystals. In both cases, this behavior results from asymmetrical\nlimitations of diffusion during grain growth.