Europium (II)-Doped Microporous Zeolite Derivatives with Enhanced Photoluminescence by Isolating Active Luminescence Centers
Solid-state reaction is the most common method for preparing luminescent materials. However, the luminescent dopants in the hosts tend to aggregate in the high-temperature annealing process, which causes adverse effect in photoluminescence. Herein, we report a novel europium (II)-doped zeolite derivative prepared by a combined ion-exchange and solid-state reaction method, in which the europium (II) ions are isolated to a large extent by the micropores of the zeolite. Excited by a broad ultraviolet band from 250 to 420 nm, a strong blue emission peaking at 450 nm was observed for these Eu-embedded zeolites annealed at 800 degrees C in a reducing atmosphere. The zeolite host with pores of molecular dimension was found to be an excellent host to isolate and stabilize the Eu2+ ions. The as-obtained europium (II)-doped zeolite derivative showed an approximately 9 fold enhancement in blue emission compared to that of the general europium (111)-doped aluminosilicates obtained by conventional solid-state reaction, indicating that, by isolating active luminescence centers, it is promising to achieve highly luminescent materials. Also, the strong blue emission with broad UV excitation band suggests a potential candidate of phosphor for ultraviolet excited light-emitting diode.