The structure and luminescence properties of Mn2+ /Eu2+ /Er3+ -doped MgO-Ga2 O3 -SiO2 glasses and glass-ceramics.

The MgO-Ga2 O3 -SiO2 glasses and glass-ceramics samples doped with Eu2+ /Mn2+ /Er3+ and heated in reductive atmosphere were prepared by the sol-gel method. The structure, morphology and the luminescence properties were studied using X-ray diffraction, high-resolution transmission electron microscope, fluorescence spectra, and up-conversion emission. The luminescence characteristics of doped ions could be influenced by temperature and matrix component. The characteristic emission of Mn2+ , Eu2+ and Er3+ were seen and the energy transfer efficiency from Eu2+ to Mn2+ was enhanced as Mn2+ concentration was increased. In addition, the two-photon process was determined for the Er3+ -doped samples.

The self-reduction synthesis and luminescent properties of Eu2+ /Eu3+ activated BaZrx Si3 O7+2x phosphors with white light emission for white light-emitting diodes.

The BaZrx Si3 O7+2x :Eu2+ /Eu3+ (2%, molar ratio) phosphors were prepared with adding different amounts of zirconium dioxide (ZrO2 ) (x = 0, 0.2, 0.4, 0.6, 0.8, and 1) by a self-reduction method under air conditions. X-ray diffraction, photoluminescence properties, thermal quenching properties and luminescent lifetimes of the prepared samples were systematically analyzed. In BaZrx Si3 O7+2x :Eu2+ /Eu3+ , both the 4f â†’ 5d transitions of Eu2+ and sharp emissions assigned to 5 D0 → 7 FJ (J = 0, 1, 2, 3, 4) transitions of Eu3+ were observed. In addition, the results also reveal that the amount of ZrO2 affects the crystal structure, the self-reduction process and further influences the relative intensity of Eu2+ /Eu3+ in all samples. Therefore, the diverse emission colors can be obtained and modulated by controlling the content of ZrO2 . The highlight of this work is that the white light emission is observed, when x is 0.4, 0.6, 0.8 and 1, respectively.

Photoluminescent properties of Eu3+ -Eu2+ activated MAl2 Six O2x + 4 (M = Mg, Ca, Sr, Ba) phosphors prepared in air.

In this paper, MAl2 Six O2x+4 :Eu2+ /Eu3+ (Eu2+ + Eu3+ = 2%, molar ratio; M = Mg, Ca, Sr, Ba; x = 0, 0.5, 1, 1.5, 2) phosphors with different SiO2 concentrations (the ratio of SiO2 to MAl2 O4 is n%, n = 0, 50, 100, 150, 200, respectively) were prepared by high-temperature solid-state reaction under atmospheric air conditions. Their structures and photoluminescent properties were systematically researched. The results indicate that Eu3+ ions have been reduced and Eu2+ ions are obtained in air through the self-reduction mechanism. The alkaline earth metal ions and doping SiO2 strongly affect the crystalline phase and photoluminescent properties of samples, including microstructures, relative intensity of Eu2+ to Eu3+ , location of emission lines/bands. It is interesting and important that the emission color and intensities of europium-doped various phosphors which consist of aluminosilicate matrices prepared under atmospheric air conditions could be modulated by changing the kinds of alkaline earth metal and the content of SiO2 .