Enhance luminescence property of Er in Bi_(0.5)Na_(0.5)TiO_3 ceramics by gradient permeation method

摘要

A method of core-shell-like gradient permeation of Er~(3+) on the surface of grain was used to prepare xEr~(3+)-Bi_(0.5)Na_(0.5)TiO_3 ceramics. The structure and photolu-minescence properties were investigated both on the gradient and homogenous doping. The XRD patterns exhibited a single rhombohedra phase. The photoluminescence measurements showed a maximum value at x= 1.5 wt% for the gradient xEr~(3+)-Bi_(0.5)Na_(0.5)TiO_3 ceramics, and a maximum value at x=2.0 wt% for the homogenous one, also critical concentrations of elimination of segregation of large strip grains. Significantly, an enhanced efficiency of bright green emission at about 550 nm was observed in the gradient Er~(3+)-Bi_(0.5)Na_(0.5)TiO_3 ceramics. In structure a critical concentration of elimination of segregation of large strip grains corresponds to the highest PL peak. The possible mechanism was discussed that concentration quenching effect is supposed due to the degeneration effect of multi-rare earth ions to allow energy transfer accompany with non-radiative loss. Gradient concentration will cause gradient overlapping energy levels to restrict energy transfer to enhance luminescence effect.