Crystal structure refinement and luminescence properties of blue-green-emitting CaSrAl2SiO7:Ce3+,Li+,Eu2+ phosphors

Abstract

Ce³⁺/Li⁺,Eu²⁺ singly doped and Ce³⁺/Li⁺/Eu²⁺-co-doped CaSrAl₂SiO₇ phosphors have been prepared using the conventional solid-state reaction method. The crystal structure of the melilite-type CaSrAl₂SiO₇ phase and the preferred crystallographic positions of the doped ions were refined using the Rietveld method. The luminescence properties and energy transfer of CaSrAl₂SiO₇:Ce³⁺,Li⁺,Eu²⁺ were studied in detail. The Ce³⁺/Li⁺ activated CaSrAl₂SiO₇ phosphor has a strong absorption band in the range of 200–450 nm and shows a blue emission centered at 477 nm. When Eu²⁺ ions are co-doped with Ce³⁺/Li⁺, the emission color of CaSrAl₂SiO₇:Ce³⁺,Li⁺,Eu²⁺ phosphors under the irradiation of 365 nm can be tuned from blue to green via the energy transfer from Ce³⁺ to Eu²⁺ ions. Also the involved energy transfer process and the corresponding mechanism between Ce³⁺ and Eu²⁺ have been discussed in detail. These results indicate that the as-reported CaSrAl₂SiO₇:Ce³⁺,Li⁺,Eu²⁺ phosphors have potential applications in near-UV chip pumped white LEDs.