Abstract
Spectral-luminescent characteristics of Sr 2Y 8(SiO 4) 6O 2: Eu powder crystal phosphor with the apatite structure and high-intensity luminescence of Eu 3+ ions have been studied. The charge state of europium in the samples has been characterized by means of X-ray L 3-adsorption spectroscopy. It was established that Eu 3+ forms two types of optical centers. Besides, luminescence of Eu 2+ions was found. Reduction Eu 3+→Eu 2+ was considered, which may be due to V Sr ∥ vacancy formation in the 4 f crystal lattice position and to negative charge transfer by this vacancy to two Eu Y 3 + ions. Thus, in the silicate lattice there exist inhomogeneously distributed oxygen-deficient centers, which are responsible for nonradiative transfer of excitation energy to Eu 3+ and Eu 2+ ions. To study electron-vibrational interactions in the crystal phosphor samples, their IR and Raman spectra were examined. In the luminescence spectrum of Eu 2+, a series of low-intensity bands caused by interaction of the 4 f 65 d state of Eu 2+ with silicate lattice vibrations was observed.
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