5d–4f emission of Eu2+ and electron-vibrational interaction in several alkaline earth sulfides doped with Eu2+ and Er3+

• Several alkaline earth sulfides doped with Eu2+ and Er3+ ions have been synthesized.
• Electron-vibrational interaction paramters are derived from the excitation and emission spectra.
• Huang–Rhys factor, effective phonon energies, and zero-phonon line positions are compared.
• Model yielded good agreement between experimental and theoretical spectra.

Several alkaline earth sulfides doped with Eu2+ and Er3+ ions have been synthesized and shown to be potential phosphors for applications in the visible spectral range. The excitation and emission spectra corresponding to the 4f–5d interconfigurational transitions of Eu2+ were analyzed with an aim of extraction of the main parameters of the electron-vibrational interaction. The values of the Huang–Rhys factor, effective phonon energies, and zero-phonon line positions were systematically compared for all studied materials; physical trends were discussed. As a test for the validity of the obtained parameters, the Eu2+ 5d–4f emission bands were modeled to yield good agreement with the experimental spectra.