Luminescence of cerium doped YAG nanopowders

Cerium doped YAG nanopowders with grain size ∼ 20 nm have been synthesized by co-precipitation method. Time-resolved luminescence characteristics have been studied. The results obtained have been compared with the luminescence characteristics for well-studied YAG single crystals. In contrast to cerium doped YAG crystals, cerium doped nanocrystal does not reveal luminescence bands due to antisite defects under electron beam pulse and X-ray excitations at 80-300 K temperature range. It was detected that decay kinetic of Ce^{3 +} related emission in the nanocrystal can be approximated by two exponents with time constants ∼ 9 and ∼ 47 ns at 290 K. It is faster than single exponential decay (∼ 80 ns) of cerium ions emission in YAG crystals. The origin of differences in luminescence characteristics for cerium doped nanocrystals and single crystals will be discussed. It is suggested that special Ce^{3 +} sites which are closely related to surface states have an influence on luminescence properties of cerium doped YAG nanocrystals.