Evaluation of the diffusion rate in the solid-phase reactions of highly refined oxides

The difference in the diffusion coefficients of cations in complex oxides during their synthesis leads to the formation of a solid solution of an oxide containing a cation with a lower diffusion coefficient in a complex oxide and a phase consisting of an oxide containing a cation with a high diffusion coefficient or enriched in this oxide. Using highly dispersed powders, it is possible to determine the most mobile cation under the conditions of synthesis by the oxide remaining in the product. This is shown by the example of the synthesis of lanthanum chromite by the sol-gel method. An explanation is given for the change in the ratio of the diffusion rates of lanthanum and chromium cations depending on the synthesis temperature and the content of polyvinyl alcohol in the gel. Bibliography: 3 titles.