Ganina I. Synthesis of activated oxide nanoparticles and modification of their luminescent properties

In the thesis sol-gel and microemulsion synthesis methods for obtaining nanodispersed powders activated by rare-earth ions (Re*2O3:Re** and Re*2SiO5:Re** compositions) for the subsequent compaction into bulk patterns have been improved and adapted. The method of "hot coordinating solvents" has been developed, which enables stable transparent colloidal solutions of nanoparticles Re2O3 for systems of biological object visualization to be obtained. Patterns of glass ceramic filled with Re-activated nanocrystals have been produced. Technological methods for controlling scintillation and luminescent properties of Re-based oxide nanocrystals have been worked out. Based on the obtained experimental data, the critical parameters for low-temperature synthesis of Re-activated oxide nanocrystals in the form of both colloidal solutions and powders have been determined. Investigations of luminescent properties of Y2SiO5:Pr3+ nanocrystals have revealed the abnormal low threshold of the 1D2 luminescence concentration quenching of Pr3+ ions as compared to the bulk crystal. It has been shown that the ascending diffusion (Gorsky effect) accounts for the Pr3+ ions moving toward a surface of the Y2SiO5 nanocrystal. In technological aspect, the Gorsky effect is shown to be used for the creation in nanoparticles and nanowires a large concentration gradient of doped ions with different ionic radii. The application of the Gorsky effect in Lu2SiO5:Ce3+ nanocrystals co-doped with Yb3+ and Dy3+ ions allows the interaction between ions to be strongly increased and an energy storage in such nanocrystals to be reduced sufficiently. A number of technological and biomedical applications of investigated nanocrystals have been demonstrated. Keywords: nanocrystal, rare-earth elements, method of synthesis, thermo-stimulated luminescence, photo-induced luminescence, luminescent image, Gorsky effect, sol-gel SiO2-matrix, nucleonic acids.