Studies on Ce2(C2O4)3·nH2O crystals grown in hydro-silica gel

Single crystals of cerium oxalate are grown by the gel method. Ce(NO3)3 is allowed to diffuse into a gel in which oxalic acid is incorporated. Cerium oxalate crystals are formed by chemical reaction and the growth process is observed. Crystals are yellow-white in colour. Morphology and size of the crystals are highly influenced by the acidity of the feed solution. With 30% HNO3 long needle shaped, with 50% HNO3 thin hexagonal and with 100% HNO3, well developed crystals are obtained. Natural etch pits are observed on the grown crystals due to the presence of HNO3. Appearance of a single, large interfacial crystal is observed for 0·5 M cerium nitrate. IR spectrum confirms the presence of water molecules and carboxylic group. X-ray diffractogram gives well defined peaks. Peaks are indexed. Unit cell dimensions are determined. Thermal analysis of the samples done using TGA and DTA show the release of water molecules (endothermic) and of CO and CO2 (exothermic) with the rare earth oxide as stable residue.