Electron-vibrational interaction in the 5d states of Eu²⁺ Ions in Sr_6-xEu_xBP₅O₂₀ (x = 0.01-0.15)

We report on the combined experimental and theoretical study of the Sr _6-xEu_xBP₅O₂₀ (x = 0.01; 0.03; 0.05; 0.07; 0.09; 0.11; 0.13; 0.15) phosphors. Spectroscopic measurements were followed by the analysis of the room-temperature absorption and emission spectra, which yielded the main parameters of the electron-phonon coupling, such as Huang-Rhys factor, Stokes shift, effective phonon energy, and zero-phonon line position. All these parameters were determined for the studied system for the first time to the best of the authors' knowledge. Reliability of the obtained parameters was checked by modeling the emission band shapes, which perfectly reproduced the experimental emission spectra of all samples.