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Information × Registration Number 0203U008029, 0100U003285 , R & D reports Title Investigation of nature and formation mechanism of magnetic properties of high anisotropic ferrimagnet macro- and nanocrystals popup.stage_title Head Kuncevich S., Registration Date 10-04-2003 Organization Kharkov National University named after V.N.Karazin popup.description2 Subject of inquiry: hexagonal ferrites of the M structure type in the form of single crystals being natural and enriched with the 57Fe isotope as well as nano- and microdispersive powders. Goal of the work: ascertaining the role of fundamental interactions in the formation of magnetic properties of macro- and nanocrystals of the highly anisotropic ferrites. Methods: static (T=80-733 R, H=22 kOe) and resonance (NMR, T=4.2-295 K, SGREMS, T=295-750 K, H=0) magnetic measurements, electron microscopy. It is determined for the first time that the main contribution to constants of the magnetic anisotropy energy and anisotropic magnetostriction of the M type ferrites is due to dipole-dipole magnetic interaction of Fe3+ ions in the 12k positions. The sublattice contributions to these constants are found. For the first time for the barium hexaferrite the low temperature deviations from the Bloch law are discovered by the NMR method. For the first time information on the magnetic structure of the crystal surfaceof the highly anisotropic barium hexaferrite is obtained directly; a contribution of the surface anisotropy to the effective magnetic anisotropy of the nanocrystal system is determined. The computer simulations of magnetization processes are made accounting for magnetocrystal and surface anisotropy and anisotropy of the particle form. The regions of existence of mixed states caused by an influence of size and surface effects are specified on the (H-T) and (T-V) diagrams of magnetic state. Product Description popup.authors popup.nrat_date 2020-04-02 Close