Gamma Radiation-Induced Synthesis of Cerium Oxide Mesocrystals

Sammanfattning: Nanoparticles of cerium dioxide was synthesized by gamma irradiation of aqueous solutions containing CeCl3 and CeBr3. ICP-OES was used to determine the precipitation yield. X-ray powder diffraction and transmission electron microscope were used to characterize the products. The crystal structurewas found by Fourier transform of high resolution electron microscope images,selected area electron diffraction, electron pair distribution function and X-ray powder diffraction. The morphology was examined from high resolution electron microscope images. The chemical composition was examined by electron energy loss spectra. Nanoparticles of 3-4 nm were found to agglomerate and fuse into cubic mesocrystals of 20-40 nm. Changing precursor did not influence the final product. An attempt to change the morphology by increasing the ionic strength with sodium perchlorate was made. At higher ionic strength, the morphology was more random and the yield increased. The size distribution also broadened. Future research can evaluate the catalytic activity of the samples, test other ions to increase the ionic strength to see if it is the ionic strength or the counterion that influences the growth, and do more analysis on the samples prepared.