Seminko V. Luminescence of dielectric nanocrystals at doped ions segregation

The thesis is devoted to the study of doped ions segregation processes influence on the luminescent properties of silicate, oxide, phosphate and vanadate RE-doped nanocrystal. In the thesis was shown that sufficient modification of luminescence concentration quenching processes in Y2SiO5:Pr3+ nanocrystals as compared to bulk crystals is caused by temperature-dependent segregation of doped ions due to relaxation of stresses created by doped ion in the crystal lattice. By means of investigation of YPO4:Pr3+ and Y2O3:Pr3+ nanocrystals it has been shown that the effect of non-uniform doped ions distribution in doped nanocrystals determined by surface impurity segregation is common for all crystal matrices in which Pr3+ ion replaces Y3+ one. Studies carried out for YVO4 nanocrystals doped with RE ions with radii larger and smaller than Y3+ radius have shown that in both cases segregation of doped ions takes place. Using YVO4: Er3+,Yb3+ as an example it was shown that the effect of doped ions non-uniform distribution within nanocrystals can be used for up-conversion luminescent processes control.