Eu3+ -Eu2+ -doped xAl2 O3 -ySiO2 and xAl2 O3 -zMgO composites phosphors.

In this paper, the Eu3+ -Eu2+ (4%, molar ratio)-doped xAl2 O3 -ySiO2 (x = 0-2.5, y = 1-5) and xAl2 O3 -zMgO (x = 0-1.5, z = 0-3) composites phosphors with different Al2 O3 to SiO2 (A/S) and Al2 O3 to MgO (A/M) ratios were prepared using a high-temperature solid-state reaction under air atmosphere. The effects of the A/S and A/M on luminescence properties, crystal structure, electron spin resonance, and Commission Internationale de l'Eclairage chromaticity coordinates of the samples were systematically analyzed. These results indicated that the different A/S and A/M ratios in the matrix effectively affected the crystal phase, degrees of self-reduction of Eu3+ , and led the relative emission intensity of Eu2+ /Eu3+ to change and adjust.

In-air self-reduction synthesis and colour tunable luminescence from SrBPO5 :Eu2+ -Eu3+ excited using ultraviolet light.

SrBPO5 :Eu2+ -Eu3+ phosphors were synthesized using a conventional solid self-reduction reaction in an air atmosphere. Samples were characterized using thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, fluorescence spectra and Commission International de l'Eclairage (CIE) data. The results of TGA and DSC showed that the raw materials could completely react at 1000°C. FTIR spectra and XRD results displayed that europium ions of different concentrations do not effect the structure of the hosts. Fluorescence spectra displayed that europium ions exist in bivalent and trivalent forms, and that the emission peak at 403 nm was attributed to the typical 5d-4f transition for Eu2+ ; 597 nm and 620 nm emissions were assigned to the characteristic transitions of 5 D0 -7F1, 2 for Eu3+ . CIE results depicted that the colour tone of the phosphors could be macro-controlled from blue to purple by controlling the doping amount of Eu3+ .Therefore, relative luminescence intensity between Eu2+ and Eu3+ could be adjusted by controlling the doping concentration of europium to tune the luminescence colour of SrBPO5 .

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.