Influence of the electron-lattice coupling for Cr^3^+ ions in Nb^5^+ site into congruent co-doped LiNbO_3: Cr^3^+: ZnO crystal

Abstract

This paper shows the important role that plays the electron-lattice coupling to represent correctly the energy levels of Cr^3^+ ions in Nb^5^+ site into congruent LiN_bO_3 crystals doped with 5.3% of ZnO. Racah's parameters: and crystal field intensity were determined and the Tanabe–Sugano's diagram was constructed. The characteristics of the absorption and emission spectra of Cr^3^+ ions in Nb^5^+ 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, are also reported in this work. Different values of breathing phonon for Cr^3^+ in Nb^5^+ site than in Li+ site could explain the higher luminescent quantum efficiency of Cr^3^+ ions located in Nb^5^+ site in LiN_bO_3 crystals.