OH- impurities in co-doped LiNbO3:Cr3+:ZnO congruent crystals

Ir optical absorption has been used to study OH-impurities into congruent co-doped LiNbO3:Cr3+:ZnO crystals doped with different Zn2+ concentration. The OH- IR absorption spectra present three bands that can be associated with different OH- complex centres available in the lattice. For crystals with lower Zn2+ concentrations ( < 4.7%) only one IR absorption band centred at 2867 nm (3490 cm-1) is reported which is associated with the OH- unperturbed vibration. For crystals with higher Zn2+ concentrations ( > 4.7%), two new bands associated with OH-vibration in distortion environment are reported. These bands are centred at 2827 nm (3537 cm-1) and 2847 nm (3512 cm-1) and can be associated with OH- -Zn2+ and Cr3+(Li+)-OH- -Zn2+(Int.) complex centres, resp. EPR has been used to identify the Cr3+ centres in the lattice of the doped LiNbO3:ZnO crystals. 19 refs.