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Tb3+ doped Ba3Gd(PO4)3 and Ba3La(PO4)3 phosphors were synthesized using the traditional high temperature solid state reaction method. The excitation, emission, and decay spectra were measured at room temperature. Efficient energy transfer (ET) from Gd3+ to Tb3+ exists in Tb3+ doped Ba3Gd(PO4)3, and the ET efficiency increases with the increase of Tb3+ concentration. The visible quantum cutting (QC) via cross relaxation was observed upon exciting low-spin (7D(J)) 5d levels of Tb3+ ions. Ba3Tb(PO4)3 sample shows relatively strong emission intensity in comparison with Zn2SiO4: Mn2+ (ZSM) upon 172 nm excitation, and with a decay time τ(1/10) about 6.4 ms under 351 nm excitation, indicating the potential application of this phosphor for plasma display panels (PDPs) and Hg-free lamps.

The VUV-vis spectroscopic properties of Tb(3+) activated fluoro-apatite phosphors Ca(6)Ln(2-x)Tb(x)Na(2)(PO(4))(6)F(2) (Ln = Gd, La) were studied. The results show that phosphors Ca(6)Gd(2-x)Tb(x)Na(2)(PO(4))(6)F(2) with Gd(3+) ions as sensitizers have intense absorption in the VUV range. The emission color of both phosphors can be tuned from blue to green by changing the doping concentration of Tb(3+) under 172 nm excitation. The visible quantum cutting (QC) via cross relaxation between Tb(3+) ions was observed in cases with and without Gd(3+). Though QC can be realized in phosphors Ca(6)La(2-x)Tb(x)Na(2)(PO(4))(6)F(2), we found that Gd(3+)-containg phosphors have a higher QC efficiency, confirming that the Gd(3+) ion indeed plays an important role during the quantum cutting process. In addition, the energy transfer process from Gd(3+) to Tb(3+) as well as (5)D(3)-(5)D(4) cross relaxation was investigated and discussed in terms of luminescence spectra and decay curves.

Ce(3+) and Eu(2+) activated Li(2)SrSiO(4) phosphors were prepared using a high temperature solid-state reaction technique. The VUV-UV-vis photoluminescence (PL) of Ce(3+)-doped phosphors Li(2-x)Sr(1-x)Ce(x)SiO(4) and Eu(2+)-doped phosphors Li(2)Sr(1-x)Eu(x)SiO(4), the low-voltage cathodoluminescence (CL) of Eu(2+)-doped phosphor Li(2)Sr(0.991-x)Eu(0.009)SiO(4) and Ce(3+)-Eu(2+) co-doped phosphors Li(2-x)Sr(0.991-x)Eu(0.009)Ce(x)SiO(4) were measured and discussed in consideration of their potential application in field emission displays (FEDs). The intense emission of phosphors Li(2-x)Sr(0.991-x)Eu(0.009)Ce(x)SiO(4) is tunable in yellow to white color gamut under low-voltage cathode ray excitation.

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