In this paper, we describe the formation and luminescence of a new garnet phosphor for light emitting diode (LED) based lighting, Lu2CaMg2(Si,Ge)3O12:Ce3+. 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 Ce3+ enters the garnet phase, giving Ce3+ luminescence that is significantly redder when compared to typical Al3+ garnet phosphors with quantum efficiencies comparable to commercial Ce3+ 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.

The effect of Si4+−N3− incorporation on Ce3+ doped RE3Al5O12:Ce3+ (RE = Lu3+, Y3+, or Tb3+) garnet phosphors is described in this report. The addition of Si4+−N3− leads to distinct low-energy Ce3+ absorption and emission bands that are assigned to Ce3+ ions that have N3− in their local coordination. The combination of the typical Ce3+ emission in garnets with the low energy Ce3+ emission band results in a broad emission spectrum suited for white LED lamps with low color temperatures and good color rendering using only a single phosphor. The low-energy Ce3+ emission band has stronger quenching at high temperatures, a potential limitation. The mechanism for this quenching is discussed.

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