A novel tunable blue-green-emitting CaGdGaAl2O7:Ce3+,Tb3+ phosphor via energy transfer for UV-excited white LEDs

Abstract

CaGdGaAl₂O₇ and CaGdGaAl₂O₇:Ce³⁺,Tb³⁺ have been synthesized by a traditional solid state reaction for the first time. The Rietveld refinement confirmed that CaGdGaAl₂O₇ has a tetragonal crystal system with the space group P21m. The photoluminescence properties show that the obtained phosphors can be efficiently excited in the range from 330 to 400 nm, which matches perfectly with commercial UV LED chips. A tunable blue-green emitting CaGdGaAl₂O₇:Ce³⁺,Tb³⁺ phosphor has been obtained, by codoping Ce³⁺ and Tb³⁺ ions into the host and varying their relative ratios, and may be a good candidate for blue-green components in UV white LEDs. The luminescence properties and lifetimes reveal an efficient energy transfer from the Ce³⁺ to Tb³⁺ ions. The energy transfer is demonstrated to be a dipole–quadrupole mechanism, and the critical distance for Ce³⁺ to Tb³⁺ calculated by the concentration quenching is 12.25 Å.