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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We report on the first observation of quantum splitting effect in nanocrystalline powders of SrAl12O19:1% Pr, Mg. The nanocrystalline materials were prepared using a surfactant-templated-assisted route yielding high-quality hexagonal nanocrystallites with thicknesses comprised between 30 and 60 nm. Comprehensive optical studies, including emission, photoexcitation, and time-resolved fluorescence measurements, demonstrate that no physical property degradation such as surface-induced loss mechanisms are found and that the quantum splitting properties of the material are fully retained in the nanocrystalline particles.

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A highly crystalline sample of the impurity stabilized phase y‐Y2Si2O7, generally known as yttrialite, has been formed from the melt of a glass with a nominal composition of 62(SiO2)–10(Al2O3)–28(Y2O3) mol%. Powder X‐ray diffraction patterns were collected using in‐house instrumentation and the 11‐BM diffractometer at the Advanced Photon Source, Argonne National Laboratory, Argonne, IL. Rietveld refinements were carried out on the patterns using two structural models. On patterns collected using in‐house instrumentation the correct structure assignment was difficult to determine; however, the extremely high‐quality data afforded by the 11‐BM instrument showed conclusively that the sample was found to crystallize in the monoclinic system (SG=P21/m) with lattice parameters a=5.03032(6), b=8.06892(6), c=7.33620(6) Å, and β=108.673(1). Furthermore, simulations have shown that it is likely that this structure model can be used to describe natural yttrialite or yttrialite that is formed at low temperatures, though the possibility that such materials are paracrystalline is also discussed.