Time-resolved luminescence of nanocrystalline inorganic complex oxides

Two types of complex nanosized oxides - cerium doped Y₃Al ₅O₁₂ (YAG) and CaWO₄- have been studied by means of time-resolved luminescence spectroscopy. Comparative study of time-resolve luminescence characteristics of cerium doped YAG single crystal, nanopowders and nanoceramic as well as for CaWO₄ macro- and nanocrystals has been done. Two components in the decay kinetic of Ce ³⁺ related emission in YAG nanocrystals were detected and it was suggested that a different energy transfer rate to volume and surface Ce ³⁺ ions takes place. It is shown that the segregation of Ce ³⁺ ions near nanoparticles surface and/or dislocation lines plays a crucial role in degradation of light yield of cerium related luminescence in YAG nanocrystals. Time-resolved properties of sol-gel synthesized CaWO₄ nanocrystals depends strongly on the synthesis rout. It was shown that shallow traps have a strong influence on the luminescence decay times of nanosized CaWO₄.