Morphology control of cerium oxide particles synthesized via a supercritical solvothermal method

Rod and sphere-like CeO₂ particles were obtained via a supercritical solvothermal method using CeCl₃.7H₂O and Ce(NO₃)₃.6H₂O as cerium sources in ethanol and methanol at 400 °C for 15 min followed by calcination in air. The rodlike particles were 200-400 nm in diameter and 1-2 μm in length. The spherical particles were 300-500 nm in diameter. The as-prepared rodlike particles using CeCl₃. 7H₂O consisted of mixtures of Ce(OH)₃ and Ce(CH₃COO)₃ and were converted to rodlike CeO ₂ by calcination in air at 500 °C. In contrast, the spherical particles prepared using Ce(NO₃)₃.6H₂O consisted of fluorite-structured CeO₂. The possible formation mechanism was discussed on the basis of the effect of reaction time on the morphology at 400 °C. The rod- and spherelike CeO₂ particles exhibited strong UV absorption below 400 nm, and the absorbance edges extend to nearly 500 nm. The rod- and spherelike CeO₂ particles exhibited near-UV emission at 360 nm and blue emission at 465 nm with higher emission intensity compared to the commercial CeO₂ sample.