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A red phosphor composed of Mn4+ embedded in host lattice of ZnSiF6·6H2O has been prepared by a one-step hydrothermal method. The host lattice ZnSiF6·6H2O is obtained from ZnF, SiO2 and HF. The luminescence center of Mn4+ is formed by incomplete reduction of KMnO4 with HF. The composition and crystal structure have been determined with measurements of XRD, EDS and infrared spectra. The thermal stability has been investigated by TG–DSC. The H2O molecules in the compound are not combined crystal water but structural water that coordinate Zn2+. The luminescence properties of phosphor ZnSiF6·6H2O:Mn4+ at 78K and 298K have been investigated. Luminescence quenches at a temperature higher than 200°C mainly which is due to the decomposition of crystal structure. [ABSTRACT FROM AUTHOR]

Abstract: Theoretical analysis of optical properties of two recently synthesized phosphors with the Ce3+ ions (Na3LuSi2O7 and NaSr4(BO3)3) was performed. The exchange charge model of crystal field was used to calculate the crystal field parameters and cerium 5d states splittings for each site in Na3LuSi2O7. Analysis of vibronic coupling of Ce3+ in NaSr4(BO3)3 resulted in a quantitative modeling and theoretical simulation of the experimental spectra. Electronic energy levels, vibrational frequencies and ion-lattice vibronic coupling strength are determined specifically for Ce3+ at different sites. The performed analysis allows for getting detailed description of the optical properties of trivalent cerium in the considered crystals and provides a general guide to understanding and characterizing other Ce3+ activated phosphors. [Copyright &y& Elsevier]