Temperature-dependent segregation of Pr3+ impurity ions in Y2SiO5:Pr3+ and YPO4:Pr3+ nanocrystals

Stationary and time-resolved spectroscopic methods are used to show that the impurity ions in Y₂SiO₅:Pr³⁺ and YPO₄:Pr³⁺ nanocrystals are distributed nonuniformly. This nonuniform distribution is found to be caused by the temperature-dependent segregation of Pr³⁺ ions near the surface of a nanocrystal. The motion of the activator ions from the bulk of a nanocrystal to the near-surface layer is traced when the activator concentration and the heat-treatment parameters are varied over wide ranges, and the main parameters of this effect (impurity redistribution intensity and time, diffusion coefficient) are estimated.