Hydrothermal Synthesis of Single Crystalline Nano CeO2 and Its Structural, Optical, and Electronic Characterization

Abstract

Single crystalline CeO2 powder was prepared by precipitation-hydrothermal technique. The hydrothermal treatment temperature and time were the two parameters chosen to observe their effect on nature of ceria. The synthesized samples were characterized for structural, optical, and electrical properties using X-ray diffraction (XRD), Fourier transform infrared (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), ultraviolet-visual (UV-Vis), and photoluminescence (PL) spectroscopy. Single crystalline CeO2 nanoparticles of about 5 to 9 nm were formed when the precipitated precursor was heated at 200°C for 3 h. The mean crystalline diameter (MCD) obtained from XRD using Scherrer's formula matched with the particle size as observed from TEM confirming the single crystalline nature of ceria. The crystallinity of sample increased with increase in reaction temperature and time while the lattice parameters decreased, as observed from XRD data. Observation from the micrographs obtained from SEM indicated the decrease in particle size as well agglomeration with increase in reaction temperature which was also confirmed by blue shift in absorption spectra of the sample obtained at 200°C. Room temperature PL spectra of CeO2 nano crystals, excited at wavelength 300 nm, showed emission at 400 and 360 nm corresponding to CeO2 synthesized at temperatures 160°C, and 200°C with corresponding E g values of 2.94 eV and 3.60 eV, respectively.