Luminescence and Microstructural Features of Eu-Activated LiBaPO₄ Phosphor

Abstract

Eu 2+ -activated LiBaPO 4 phosphor was synthesized by conventional solid-state reaction. The photoluminescence excitation and emission spectra, the temperature dependent luminescence intensities (12−450 K), and decay curves of the phosphor were investigated. With the increasing of temperatures, the emission bands of LiBaPO 4:Eu 2+ show the abnormal blue-shift and the decreasing of emission intensity. The natures of the Eu 2+ emission in LiBaPO 4, for example, the luminescence quenching temperature, and the activation energy for thermal quenching (Δ E ), were reported. The afterglow fluorescence was detected in LiBaPO 4:Eu 2+ phosphor. Together with the Eu 2+ luminescence, Eu 3+ ions with the abnormal crystal field were observed. The site-selective excitation in the 5 D 0 → 7 F 0 region for Eu 3+ ions, emission spectra, and decay curves have been investigated using a pulsed, tunable, and narrowband dye laser to detect the microstructure and crystallographic surrounding of Eu 3+,2+ at Ba 2+ sites in LiBaPO 4 . The multiple sites structure of Eu 2+ and Eu 3+ ions in LiBaPO 4 lattices was suggested. The lower quenching temperature, afterglow, and luminescence mechanism were discussed. The photoluminescence quantum efficiencies of LiBaPO 4:Eu 2+ were measured and compared with the reported phosphors. Different from the published data on LiBaPO 4:Eu 2+, this investigation indicates that LiBaPO 4:Eu 2+ is not a good phosphor candidate applied in white light emitting diode.