Novel transparent luminescent glass ceramics with the ability to generate the line emission of Eu2+ ions were successfully prepared. First, Eu2+-doped barium–aluminum–borate oxyfluoride glasses were prepared by high-temperature melting in a reducing atmosphere, and then transparent glass ceramics were obtained by crystallization heat treatment. Fluorescence spectroscopy showed that Eu2+ exhibited only broadband luminescence (FWHM ≈ 136 nm) of the 4f65d1 → 4f7 transition in the glasses. However, after heat treatment, a 359 nm line emission (FWHM ≈ 2.8 nm) from the 4f7 → 4f7 transition of Eu2+ appeared in the glass ceramics. To explore the mechanism of transformation of the optical transition of Eu2+ from 4f65d1 → 4f7 to 4f7 → 4f7, the glasses and glass ceramics were analyzed by fluorescence spectroscopy, X-ray diffraction (XRD), Raman spectroscopy, and electron paramagnetic resonance (EPR) spectroscopy measurements. The results showed that the alteration in the optical transition of Eu2+ was a result of the Eu2+ ions entering the Ba2+ sites with weak crystal field strength in BaAlBO3F2 (BABF) crystals from the strong crystal field strength glass phase.
High quantum efficiency and thermal stability have always been the goals to pursue and challenges for lighting application. In this work, sunlight-like white emission has been achieved in a new prepared single phased Rb 2 CaP 2 O 7 : 0.005Ce 3+ , 0.01Eu 2+ phosphor, which exhibits high internal quantum efficiency (IQE = 74.36%), external (EQE = 56.77%) quantum efficiency and excellent thermal stability. Based on the broadband emission from 4f-5d transitions of Ce 3+ /Eu 2+ ions and high energy transfer efficiency of Ce 3+ →Eu 2+ (measured up to 60%), the extremely wide color-tunable emission from blue-violet to white and then to orange-yellow is realized in Rb 2 CaP 2 O 7 : 0.005Ce 3+ , xEu 2+ phosphors. Moreover, a prototype WLED device is packaged by combing the prepared Ra 2 CaP 2 O 7 : 0.005Ce 3+ , 0.01Eu 2+ white phosphors with an UV LED chip (λ = 310 nm), and the obtained WLED emits bright sunlight-like white light with color coordinates of (0.377, 0.324). The correlated color temperature (CCT) and the color rendering index (CRI) value of the WLED are 3208 K and 88.4, respectively. These results can provide effective guidance for the design of color-tunable single-phase white phosphors with high luminous efficacy and thermal stability.
危险品化学品经营许可证（带存储）