Energy transfer between Ce 3+ and Tb 3+ and the enhanced luminescence of a green phosphor SrB 2 O 4 :Ce 3+ , Tb 3+ , Na +

A series of Ce3+ or Tb3+ doped and Ce3+, Tb3+, and Na+ co-doped SrB2O4 phosphors were synthesized by solid-state reaction method. Luminescence intensity was increased as M+ (M+ = Li+, Na+, K+) ions were used to compensate the valance in SrB2O4:Ce3+, in which the charge compensation by Na+ ion in SrB2O4:Ce3+ showed the strongest luminescence intensity. When the content of Ce3+ was fixed at 2 mol. % by tuning the contents of Tb3+ ions from 1 mol. % to 10 mol. %, SrB2O4:0.02Ce3+, yTb3+, zNa+ showed both an emission (360 nm) from Ce3+ and a yellowish-green emission (541 nm) from Tb3+, which disclose that an effective energy transfer from Ce3+ to Tb3+ exists in the phosphor. The energy transfer efficiency reaches as high as 80.2% for a Tb3+ concentration of 10 mol. %. The QE of SrB2O4:0.02Ce3+,0.03Tb3+, SrB2O4:0.02Ce3+, 0.03Tb3+, 0.05Na+ phosphors are 41.3% and 54.7% excited at 319 nm. The energy transfer mechanism was proved to be dipole–dipole interaction. The CIE chromaticity coordinates of the optimized SrB2O4:0.02Ce3+, 0.03Tb3+, 0.05Na+ phosphor, which were thermal stable revealed by temperature-dependent PL results, were calculated to be (0.3035, 0.4812).