Yu-Chun Li

High color purity phosphors of LaAlGe2O7 doped with Tm3+ and Er3+

Phosphors of LaAlGe2O7 doped with Tm3+ and Er3+ of high color purity, exhibiting a narrow band emission in the blue and green regions, were obtained. (La1−xLnx)AlGe2O7 (Ln=Tm,Er) 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 Tm3+-doped phosphor had CIE chromaticity coordinates (0.151, 0.033) with a dominant wavelength of 455nm and a color purity of 94%. The Er3+-doped phosphor had color coordinates (0.249, 0.718), a dominant wavelength of 542nm, and 92% purity.

Green-emitting phosphor of LaAlGe2O7:Tb3+under Near-UV irradiation

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 (LED) have closely overlapped, which provides the potential as a near-UV LED converted phosphor in solid state lighting technology.