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Abstract: Sn2+- and Sn2+/Mn2+-doped α-Sr2P2O7 phosphors have been synthesized by using the traditional solid-state reaction. The photoluminescence of Sn2+ and Sn2+/Mn2+ in α-Sr2P2O7 are reported and discussed. The Sn2+-activated material exhibits a blue-emitting band peaking at about 450nm under UV excitation. The Mn2+ emission peaking at about 565nm of Sn2+/Mn2+ co-doped samples can be enhanced through energy transfer from Sn2+ to Mn2+. Combining emission colors of Sn2+ and Mn2+ under UV excitation, white light emission can be achieved. [Copyright &y& Elsevier]

Abstract: Infrared to visible up-conversion emissions in Yb3+–Er3+ co-doped KGd2F7 samples excited at 980 nm are presented in this paper. Green (2H11/2,4S3/2→4I15/2), red (4F9/2→4I15/2) and violet (2H9/2→4I15/2) emissions are observed under low pumping power, and the green emission is dominant. The dependences of these emissions as function of the pumping power intensities and the doped rare-earth ion concentrations are described. The results indicate that the green and red emission of Er3+ ion result from two-photon excitation processes, and the violet emission of Er3+ ion from three-photon processes. The most efficient composition for green emission is 2–4 mol% Er3+ and 10–20 mol% Yb3+ in synthesized samples. The mechanisms for explaining these up-conversion properties have been provided. [Copyright &y& Elsevier]

Abstract: Novel phosphors of Eu2+-doped (Ca1−xSrx)Se for the application of white light emitting diodes (LEDs) were prepared by conventional solid-state reaction. Diffuse reflection spectra of CaSe, SrSe, CaSe:Eu2+ and SrSe:Eu2+ were measured. The excitation spectra consisted of two broad bands and were consistent with the diffuse reflectance spectra. The emission band is due to the 4f65d1→4f7 transition of the Eu2+ ion. With an increase in x, the emission band shifted to shorter wavelength and the reason was discussed. The fluorescence lifetimes of Eu2+ in (Ca1−xSrx)Se:0.04Eu2+ were also measured and the values were reasonable for the allowed transition 4f65d1→4f7 in Eu2+. [Copyright &y& Elsevier]

Abstract: A novel blue-emitting Sr3Al2O5Cl2:Ce3+,Li+ phosphor has been synthesized by solid state reaction. The excitation spectrum shows a broad band extending from 300 to 400 nm, and the emission spectrum shows a broad blue band peaking at 450 nm with a half width of about 100 nm. The emission intensity at 250 °C remains at about 50% of that at room temperature. The decay curve at the emission peak consists of fast and slow components. The Sr3Al2O5Cl2:Ce3+,Li+ should be a promising blue phosphor for near ultraviolet-based white-light-emitting diodes. [Copyright &y& Elsevier]

Abstract: (Ca1+ x − y Eu y )Ga2S4+ x phosphors have been synthesized one step by solid state reaction. The photoluminescence excitation and emission spectra of phosphors have been studied; the influence of host composition and Eu2+ concentration on emission spectra has also been investigated. The emission spectrum consists of yellow emission at 550 nm and red emission at 650 nm. It also indicates that the excitation spectrum is a broadband and can be well matched with the emission of GaN chip. Combined these phosphors with 460 nm-emitting GaN chips, White LEDs have been fabricated. Their electroluminescence spectra have been measured under 20 mA forward-bias current. Their CIE chromaticity coordinates and color temperature indicate that (Ca1+ x − y Eu y )Ga2S4+ x phosphors are promising phosphors for GaN-based white LEDs. [Copyright &y& Elsevier]

Abstract: A novel blue-emitting Sr3Ga2O5Cl2:Eu2+ phosphor has been synthesized by a two-step solid-state reaction. The luminescence properties have been investigated by photoluminescence (PL) spectra, and temperature-dependent PL spectra. It shows an efficient broad absorption band around 400nm, which matches well with the commercial near-ultraviolet light-emitting chips, and an efficient blue emission. It shows a higher thermal quenching temperature than that of Sr3Al2O5Cl2:Eu2+ phosphor. Sr3Ga2O5Cl2:Eu2+ phosphor is a promising blue-emitting component for UV chip excited white light-emitting-diodes. [Copyright &y& Elsevier]

The growth of novel birefringent crystal α-BaB2O4 by the modified Bridgman method has been reported in this paper. By means of the optimum conditions such as stoichiometric feed materials, sealed platinum crucibles, [001] growth direction, growth rate less than 0.3 mm/h and convex or plane solid–liquid interface with temperature gradient 30–40 °C/cm, large-size crystals without macro-defects have been grown successfully. [Copyright &y& Elsevier]