Tailoring the Luminescence of Europium Ions in Mesoporous AlPO4 Monolithic Glass

Controllable simultaneous luminescent monolithic mesoporous AlPO4 glasses doped with Eu ions were fabricated by dipping into a Eu-containing solution, followed by sintering in air. Reduction of partial Eu3+ ions to Eu2+ were achieved after annealing Eu3+ ions in AlPO4 meso-structure, which resulted in simultaneous luminescence of Eu3+ (590 and 613 nm) and Eu2+ (450 nm). Controllable luminescence and color tunability from blue to red were liable to obtain, which were characterized by emission spectra and described by CIE diagram. A deliberate tailoring of luminescence of Eu2+ and Eu3+ is achieved by controlling the Eu ions concentrations, sintering temperatures, and excitation wavelengths. Reduction and oxidation reactions of Eu ions were investigated by controlling the sintering atmospheres. XRD pattern indicated the typical amorphous glassy phase without obvious phase-separation even in high concentration (0.1 M). The presence of Eu2+ ions, which were reduced from Eu3+ by hole electron pairs and diffused into mesoporous structure, was revealed by XPS spectra.