The influence of the specific surface of grains on the luminescence properties of Nd3+ -doped Y3Al5O12 nanopowders

Nd3+: Y3Al5O12 (Nd: YAG) powders were prepared by the Pechini method in the temperature range of 800 to 1400 degrees C. The pure garnet phase of the obtained materials was confirmed by XRD studies. The size of the grains was controlled by the annealing temperature of the samples. Their morphologies were investigated by TEM and porosity measurements ( BET). The effect of annealing temperature on the morphology and luminescence properties of Nd: YAG nanocrystallites was studied, and the results were compared to the properties of a Nd: YAG single crystal. A significant enhancement of the F-4(3/2) -> (4) I-9/2/F-4(3)/2 -> (4) I-11/2 intensity ratio with decreasing grain size was observed. It was found that the decay times of the Nd3+ luminescence depends on the specific surface and is significantly longer for well crystallized nanocrystalline grains than for single crystals having the same concentration of Nd3+ ions. The role of crystallinity and specific surface on the radiative processes is analyzed.