Nanocrystalline cerium oxide powder

One of the major motivations for the development of the WPPM approach is provided by the growing field of nanomaterials. Knowing the distribution of crystalline domains is a basic piece of information in nanotechnology. In many cases, as in the example considered below, this information is particularly valuable because it is equivalent to the grain size distribution. It is frequently observed in nanocrystalline materials that grains are single crystalline domains in these cases, one can expect a close match between WPPM results and a size distribution obtained by other techniques, like HREM. 

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Figure 13.17 WPPM results for a nanocrystalline cerium oxide powder. Experimental data (O) profile fitting result (line) and difference between data and fit (residual, lower line). Inset Log scale plot and Miller indices of Bragg peaks. (Reprinted from ref. 58 with the permission of the International Union of Crystallography.)...

Nanocrystalline cerium (IV) oxide powders with an average particle size of 10 -14 nm have been prepared by the cathodic base electrogeneration method.The nanocrystallinc CeO powders are prepared in the cathode compartment of a divided electrochemical cell. The cathode is a platinum wire and the anode is a platinum mesh electrode. The cathode compartment in the divided cell contained 0.5 mol T cerium (HI) nitrate and 0.5 moM ammonium niu-ate, and the anode compartment contained 0.5 mol I ammonium nitrate. The two compartments are separated with a medium porosity glass frit. The electrochemical synthesis is run in the galvanostatic mode at a current density of I A cm and the particle size is controlled by adjusting the solution temperature. 

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