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The magnetic properties of ZnO:Mn(2at%) nanocrystals synthesized by ultrasonic aerosol pyrolysis were studied. It has been established that short-term thermal treatment in hydrogen does not affect the magnetization of the synthesized sample, which had ferromagnetic and paramagnetic components. The sample, which underwent heat treatment in air at T = 850°C and acquired paramagnetic properties, after heat treatment in hydrogen again became ferromagnetic without a paramagnetic phase. It has been established by the EPR method that the structure of defects in the synthesized ZnO:Mn(2%) NCs is inhomogeneous. It changes after heat treatment in hydrogen. It is shown that the controlled thermal treatment of the samples, first in air and then in hydrogen, makes it possible to predictably change their magnetic properties. The results obtained are explained using the model of coupled magnetic polarons. During thermal treatment in hydrogen, the ratio of the number of oxygen vacancies Vo and interstitial Mn2+ ions changes in the samples.

The article is devoted to the analysis of changes in the magnetic characteristics of ferrites in the CoO-NiO-ZnO system by the simplex method. Ferrites of Ni-Zn, Co-Zn, and Co-Ni were synthesized in the form of nanoparticles (20-40 nm) using a new method for processing contact nonequilibrium low-temperature plasma (CNP). The effect of the mutual influence of the contents of different cations on the saturation magnetization and the coercive field was investigated using the simplexlattice method. A magnetic investigation using a vibrational magnetometer shows that low magnetization values are observed for Ni-Zn ferrites and high for the entire Co-Zn and Co-Ni ferrite series. EPR spectra show that the value of the resonant field and line width corresponds to the value of magnetic saturation and is due to the arrangement of cations on sublattices.