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Abstract: Ce3+/Eu2+ co-doped Li2SrSiO4 phosphor yields two emission bands consisted of blue and yellow components, which shows great potential as single host white phosphor for white LEDs. Effective energy transfer occurs in Ce3+/Eu2+ co-doped Li2SrSiO4 due to large spectral overlap between the emission of Ce3+ and excitation of Eu2+. Co-doping of Ce3+ enhances the emission intensity of Eu2+ greatly by transferring its excitation energy to Eu2+. The Ce3+ →Eu2+ energy transfer, thoroughly investigated by their absorption, excitation and photoluminescence decay behaviors, is demonstrated to be in the mechanism of electric dipole–dipole interaction. [Copyright &y& Elsevier]

Abstract: The crystal structure and photoluminescence properties of Eu2+ doped Li2Ca0.7Sr0.3SiO4 phosphors were investigated. The Li2Ca0.7Sr0.3SiO4 is not an alloy between the tetragonal Li2CaSiO4 and hexagonal Li2SrSiO4 but crystallizes in orthorhombic structure similar to Li2(CaSr)SiO4. Photoluminescence properties of the Li2Ca0.7Sr0.3SiO4:Eu2+ phosphors, summarized in effective excitation in the UV region, strong emission in the blue light range (with a peak at 427nm) and the CIE chromaticity coordinate (0.154, 0.038), indicate this phosphor has great potential in UV-chip pumped white LEDs. White light output by mixing the Li2Ca0.7Sr0.3SiO4:Eu2+ blue and Li2SrSiO4:Eu2+ yellow phosphor was attempted. With proper molar ratio of these two compound phosphors, warm white light with CIE chromaticity coordinate close to that of the nature white light (0.33, 0.33) and color temperature about 5000K was obtained. The results indicated that the Li2Ca0.7Sr0.3SiO4:Eu2+ may become an important phosphor candidate for ultra-violet chip pumped and multi-phosphors converted white LEDs. [Copyright &y& Elsevier]