Oxygen Isotope Exchange in Nanocrystal Oxide Powders

It is shown that investigations of the isotope exchange kinetics in nanocrystalline oxides allows one not only to solve problems connected with determination of process parameters and characteristic scenarios, but also to substantially extend experimental opportunities in analysis of diffusion properties of oxides. A specific behavior of the oxygen isotope exchange was studied in nanocrystalline LaMnO3 and ZrO2:Y2O3 oxides. The former oxide is characterized by very small values of oxygen volume diffusion coefficients, while the latter one is, on the contrary, an ionic conductor. The study was carried out using powdered nanomaterials prepared from original ceramic materials by grinding in planetary mills or by laser evaporation. The study revealed future trends in the use of nanomaterials for analysis of the diffusion kinetics in oxides. It is demonstrated that in this case the sensitivity of traditional isotope methods increases considerably and fundamentally new opportunities are provided for analysis of processes on the "gas phase  solid state" interface as well as for the study of volume diffusion in polycrystals. Considering a strong dependence of the isotope exchange rate on the particle size, it is also topical to conduct studies dealing, along with determination of kinetic parameters of the process, with the use of the obtained data for certification of dimensional characteristics of oxide nanopowders.