Synthesis and spectral characteristics of Sr2Y8(SiO4)6O2: Eu polycrystals

Spectral-luminescent characteristics of Sr2Y8(SiO4)6O2: Eu powder crystal phosphor with the apatite structure and high-intensity luminescence of Eu3+ ions have been studied. The charge state of europium in the samples has been characterized by means of X-ray L3-adsorption spectroscopy. It was established that Eu3+ forms two types of optical centers. Besides, luminescence of Eu2+ions was found. Reduction Eu3+→Eu2+ was considered, which may be due to View the MathML sourceVSr∥ vacancy formation in the 4f crystal lattice position and to negative charge transfer by this vacancy to two View the MathML sourceEuY3+ ions. Thus, in the silicate lattice there exist inhomogeneously distributed oxygen-deficient centers, which are responsible for nonradiative transfer of excitation energy to Eu3+ and Eu2+ ions. To study electron-vibrational interactions in the crystal phosphor samples, their IR and Raman spectra were examined. In the luminescence spectrum of Eu2+, a series of low-intensity bands caused by interaction of the 4f65d state of Eu2+ with silicate lattice vibrations was observed.