Ivakhnenko N. Evolution of clustered structure with changing ferrospinel composition and annealing duration

The thesis is devoted to determining the regularities of quasi-equilibrium mesoscopic size formations (clusters), differing by composition, atomic or electronic structure, in the matrix structure of Mn-Zn and Mg-Zn ferrites. Mn-Zn ferrites differ in mass concentration of native oxides while Mg-Zn ferrites differ in annealing time from 0.5h to 8h at T=1280C. Cluster is a family of well-developed plane fragments having the appearance of diffuse stripes between narrow Debye lines of basic structure on diffraction pattern. X-ray diffraction and X-ray spectrum methods are used for the analysis of clustered structures. It is demonstrated that changing of chemical composition of Mn-Zn ferrites results in development of mesoscopic size clusters involving ionization changing of Mn ions (from bivalent to the trivalent manganese). Mg-Zn ferrite structures are found to feature inhomogeneously layered distribution of chemical elements. Matrix structure in Mg-Zn ferrites demonstrates changing from homogeneous state to heterogeneous state with annealing time from 1h to 2h annealing, and subsequent phase transition from a stratified ordered solid solution to a stable state after 2h. It is established that high-energy state intensity increases in emission spectrums of iron, which indicates the increased fraction of collective electrode states with a 2 hour annealing period in comparison to localized states domineering at 1h. It is shown that clusters in Mn-Zn and Mg-Zn ferrites cause changing of physical properties.