Luminescence and Energy Transfer of Dual-Emitting Solid Solution Phosphors (Ca,Sr)10Li(PO4)7:Ce3+,Mn2+ for Ratiometric Temperature Sensing

A series of novel dual-emitting solid solution phosphors, (Ca,Sr)(10)Li(PO4)(7): Ce3+, Mn2+ (CSLP:Ce3+,Mn2+), were synthesized by high-temperature solid-state method. CSLP:Ce3+,Mn2+ exhibits both CO3+ violet emission and Mn2+ red emission under UV excitation. It is found that Sr'+ partial substitution of Ca2+ could result in enhancement of Mn2+ emission intensity and blue-shift of Mn2+ emission wavelength, which is due to site symmetry reduction and polyhedron expansion, respectively. The Ce3+-Mn2+ energy transfer (ET) is efficient (similar to 90%), and the ET mechanism is dipole dipole interaction. The application potential of CSLP:Ce3+,Mn2+ in optical thermometry was studied by exploiting the temperature sensitivity of the fluorescent intensity ratio (violet/red). It is found that the intensity ratio of the Ce3+ and Mn2+ emission peak linearly related to the temperature from 293 to 473 K with sensitivity of 0.40% K-1. These results reveal that CSLP:Ce3+,Mn2+ may be a potential candidate for a luminescent ratiometric thermometer with wide temperature range.