Luminescence centers in bismuth-containing oxytungstate ceramics

We have studied the photoexcitation and luminescence spectra of Bi2WO6, Y2WO6 and Y2WO6:Bi ceramics. We used the Alentsev-Fock method to decompose the spectra into elementary components. The emission bands with maximum at 2.93 eV in the luminescence spectrum of Bi2WO6, 3.02 eV in the luminescence spectrum of Y2WO6, and 2.95 eV in the luminescence spectrum of Y2WO6:Bi are assigned to luminescence of self-localized Frenkel excitons. The bands with maxima at 2.35 eV and 1.90 eV in the spectrum of Bi2WO6, 2.25 eV and 1.75 eV in the spectrum of Y2WO6, and 2.35 eV and 1.85 eV in the spectrum of Y2WO6:Bi are connected with oxygen vacancies.