Influence of the electron-lattice coupling for Cr3+ ions in Nb5+ site into congruent co-doped LiNbO3:: Cr3+: ZnO crystal

This paper shows the important role that plays the electron-lattice coupling to represent correctly the energy levels of Cr3+ ions in Nb5+ Site into congruent LiNbO3 crystals doped with 5.3% of ZnO. Racah's parameters: B = 646 cm(-1), C = 3022 cm(-1) and crystal field intensity Dq = 1342 cm(-1) were determined and the Tanabe-Sugano's diagram was constructed. The characteristics of the absorption and emission spectra of Cr3+ ions in Nb5+ site have been explained in terms of the Configurational Co-ordinate model in the harmonic approximation. Huang-Rhys parameter, S = 3.5 and the breathing phonon energy. homega = 460 cm(-1), are also reported in this work. Different values of breathing phonon for Cr3+ in Nb5+ site than in Li+ site could explain the higher luminescent quantum efficiency of Cr3+ ions located in Nb5+ site in LiNbO3 crystals. (C) 2003 Elsevier Ltd. All rights reserved.