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

Abstract 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, ℏω=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.

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