Crystal Chemistry and Luminescence of Ce3+-Doped Lu2CaMg2(Si,Ge)3O12 and Its Use in LED Based Lighting

In this paper, we describe the formation and luminescence of a new garnet phosphor for light emitting diode (LED) based lighting, Lu 2 CaMg 2 (Si,Ge) 3 O 12:Ce 3+ . The regions for garnet phase formation are initially described with respect to larger rare earth substitution and show reasonable correlation to previous crystal chemistry studies for the garnet parent structure. While the pure silicate phosphor also has apatite second phases, a significant amount of Ce 3+ enters the garnet phase, giving Ce 3+ luminescence that is significantly redder when compared to typical Al 3+ garnet phosphors with quantum efficiencies comparable to commercial Ce 3+ garnet phosphors. Potential reasons for the emission red shift and the high quantum efficiency are discussed. Finally, the performance of these new phosphors is tested within LED based lamps. Lamps using these phosphors can reach color temperatures required for general illumination lighting and also have comparable phosphor conversion efficiencies when compared to lamps using typical garnet phosphors.