Synthesis of nanocrystalline cerium oxide particles by the precipitation method

Effects of reaction temperature and atmosphere on properties of the CeO2 particles prepared by the precipitation technique, including particle size, shape, and crystalline structure were investigated. Also, the bandgap, energies were estimated from the UV absorption spectra. Experimental results showed that the prepared particles were primary, non-porous and with cubic fluorite structure. The reaction temperature and oxygen content of O-2/N-2 atmosphere played important roles on the size and shape of resulting particles. The average particle size as well as the crystallite size increased with increasing the reaction temperature and decreasing the oxygen content. Besides, the particle shape transformed from square-like to hexagonal as the temperature was raised from 30 to 90 degrees C. In oxygen-lean atmosphere, the shape of all resulting particles was hexagonal, whereas needles mixed with hexagonal particles found at above 50% O-2. Due to the quantum confinement effect, the bandgap energies of particles over the studied conditions approximately increased with decreasing particle size. However, the oxygen-induced shape change exhibited an exceptional deviation. (c) 2004 Elsevier Ltd and Techna Group S.r.l. All rights reserved.