Vibrational spectra, electronic transitions and short order structure of rare earth—gallium sulphide glasses

Abstract

Absorption spectra of chalcogenide glasses of general formula Ln 2S 3-1,8 Ga 2S 3 (Ln = La +3, Ce +3, Pr +3, Nd +3, Gd +3) were investigated from the far infrared to ultra-violet region. Raman spectra were recorded in the 5 cm −1–600 cm −1 range. Vibrational spectra of glasses have been compared with those of polycrystalline compounds Ln 10 3 Ga 6S 14 (Ln = La +3, Ce +3) and Ln 6Ga 10 3 S 14 (Ln = La +3 to Gd +3). From the observed spectra it could be concluded that the short distance order around gallium atom is strongly modified in going from crystalline to glassy state. Electronic transitions of Ce +3, Pr +3 and Nd +3 ions have been also identified in the visible region and in the mid infrared absorption spectra.