Novel red-emitting phosphor Ca9Y(PO4)7:Ce3+,Mn2+ with energy transfer for fluorescent lamp application

A series of new luminescent emission-tunable phosphors Ca(9)Y(PO(4))(7):zCe(3+),xMn(2+) have been synthesized by a high-temperature solid-state reaction. We report a broad deep red-emitting composition-optimized phosphor (Ca(0.9))(9)Y(0.85)(PO(4))(7):0.15Ce(3+),0.1Mn(2+), which has been found to be feasible for the application in fluorescent lamps. The Commission Internationale de I'Eclairage (CIE) chromaticity coordinates measured for the phosphor were (0.68, 0.29), and those for fluorescent lamps with and without a 600 nm filter were found to be (0.67, 0.29) and (0.54, 0.32), respectively. The Ca(9)Y(PO(4))(7):Ce(3+),Mn(2+) phosphor showed two emission bands under 254 nm excitation: the one observed at 366 nm was attributed to Ce(3+) ion emission, and the other found at 650 nm was assigned to the emission from Mn(2+) ions. We have shown that the mechanism of energy transfer from Ce(3+) to Mn(2+) was of the resonance type and it occurred via an electric dipole-quadrupole interaction. Furthermore, we have calculated the critical distance for Ce(3+) --> Mn(2+) energy transfer to be 13.45 A by concentration quenching methods.