Microstructure and optical characteristics of rod-like nanoscale CeO2 synthesized by hydrothermal method

The rod-like nanoscale CeO2 were successfully synthesized by an ethanediamine-assisted hydrothermal synthesis process using CeCl3 x 7H2O as cerium source and N2H4 x H2O as mineralizer. The morphology, microstructure, and optical properties of nanoscale CeO2 were characterized by the scanning electron microscope, transmission electron microscope, X-ray diffraction, X-ray photoelectron spectroscopy, Raman spectrometer, UV-Vis spectrophotometer and photoluminescence spectrometer. The lattice parameter decreases with the increase of crystallite size due to the effect of lattice relaxation and Ce ions. Suitable amount of ethylenediamine is beneficial for the growth of CeO2 nanorods. The as-growth rod-like nanoscale CeO2 is polycrystalline materials, and the main valence of cerium was +4. The spectra exhibit a strong absorption band at the near UV region due to the charge-transfer transitions from O 2p to Ce 4f. The band gap energy increases with the increase of ethylenediamine from 0 up to 3 mL and then decreases. Photoluminescence properties were measured using the 325 nm line of He-Cd laser and were also discussed.