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Spectra of photoluminescence (PL), luminescence excitation, stationary and photoactivated optical absorptions and photoconductivity are studied for Bi 12 SiO 20 crystals. The PL spectra contain wide bands, of which shapes differ for the cases of electronic valence-to-conduction band excitation (the photon energies hν = 3.3-4.0 eV) and the excitation occurring from the impurity absorption band (hν = 2.8-2.9 eV). The photochromic effect and the induced impurity photoconductivity are also observed. Recombination and intra-centre mechanisms of the PL are discussed.

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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.

Samples of ZnO:Mn nanocrystals with Mn concentrations of 2 and 4 at.% were synthesized by ultrasonic aerosol pyrolysis. The synthesis was carried out at 550°C using aqueous solutions of zinc and manganese nitrates. The samples obtained were subjected to heat treatment at 550°C and 850°C in air for 1 hour. The study of the samples by XRD and EPR methods shows that during the synthesis the process of doping ZnO nanocrystals with manganese occurs only partially, on the surface, in the near-surface layer. Residues of the Mn impurity are located on the surface of nanocrystals and appear during annealing at 550°С in the form of manganese oxides (Mn2O3). During heat treatment at 850°C, decomposition of Mn2O3 and bulk doping of ZnO:Mn nanocrystals occur.