Premium
Structural and Optical Properties of the System (Sr, Eu) 5 (PO 4 ) 3 (Cl,F)
Author(s) -
Nötzold D.,
Wulff H.
Publication year - 1998
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/(sici)1521-3951(199805)207:1<271::aid-pssb271>3.0.co;2-y
Subject(s) - political science , materials science , business , chemistry
Mixed crystals of the composition Sr 5− y Eu y (PO 4 ) 3 Cl 1− x F x with 0 ≤ x ≤ 1 and 0 ≤ y ≤ 0.05 were prepared by solid state reaction. The crystal structure, optical properties at room temperature, and the emission spectra of the polycrystalline materials at liquid nitrogen temperature are investigated. The structure parameters are refined by the Rietveld method. The space group of the mixed crystals is P6 3 /m. The position of the halide ions in the unit cell depends on the fluoride content in the materials. Eu 2+ ions occupy preferentially 6h cation positions of the unit cell. The lattice constant a 0 decreases but c 0 increases with increasing fluoride content in the samples and the emission band due to transitions between 4f 6 5d and 4f 7 configurations of the Eu 2+ ions is shifted to higher energies. The shape of the excitation spectrum and the fluorescence lifetime change when the fluoride content in the mixed crystals exceeds the chloride content.