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Phosphors of LaAlGe 2 O 7 doped with Tm 3+ and Er 3+ of high color purity, exhibiting a narrow band emission in the blue and green regions, were obtained. ͑La 1−x Ln x ͒AlGe 2 O 7 ͑Ln= Tm, Er͒ powders are bright emitters, with chromaticity color coordinates that are comparable to or better than those of standard phosphors for display or lighting devices. The blue emission of the Tm 3+-doped phosphor had CIE chromaticity coordinates ͑0.151, 0.033͒ with a dominant wavelength of 455 nm and a color purity of 94%. The Er 3+-doped phosphor had color coordinates ͑0.249, 0.718͒, a dominant wavelength of 542 nm, and 92% purity.

The novel phosphors of LaAlGe 2 O 7 doped with Gd 3+ and Tb 3+ were synthesized, and their luminescence properties were investigated. In Tb 3+ -activated LaAlGe 2 O 7 , the unusual excitation spectra showed only intense f-f transition of Tb 3+ ions around the near-UV region, whereas the 4f-5d transition could be neglected. In the Gd 3+ -Tb 3+ -activated system, the decay time of Tb 3+ emission under Gd 3+ excitation at the 6 I J energy level was longer than that measured under direct Tb 3+ excitation at the 5 L 10 energy level, which reinforces the existence of effective Gd 3+ -to-Tb 3+ energy transfer. In the 5 D 4 decay measurements, time-resolved spectra exhibited a "grow-in" behavior as the Tb 3+ concentration was diluted (<0.03 mol), whereas only a simple exponential decay could be observed at higher (>0.05 mol) Tb 3+ concentrations. Two linear relationships were found between the energy transfer probability (P GdfTb ) and the Tb 3+ concentration, which is clear evidence that there were two kinds of efficient Gd 3+ -to-Tb 3+ energy transfer processes in terms of Tb 3+ concentration.

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As the Tb 3+ -doped LaAlGe 2 O 7 phosphors were synthesized by solid-state method, their characterization and luminescent properties were also investigated. The extraordinary excitation spectra showed only intense f-f transition of Tb 3+ ions around near-UV region, while the 4f-5d transition could be neglected. Under excitation, the as-obtained powders emitted bright green light at 544 nm ͑ 5 D 4 → 7 F 5 ͒. By analyzing the decay curves, the energy migration between Tb 3+ ions is conspicuous in 5 D 3 → 7 F 5 transition due to the cross-relaxation in LaAlGe 2 O 7 . One of the interesting results of this work is that the excitation spectrum of the phosphor and the emission spectrum of the near-UV light-emitting diode ͑LED͒ have closely overlapped, which provides the potential as a near-UV LED converted phosphor in solid state lighting technology.

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