The OH−absorption spectrum as a probe of defect structure of LiNbO3crystal

Abstract

Abstract The OH− infrared absorption band in the LiNbO3 crystal with various Li/Nb ratios and contents of MgO have been measured at room temperature. The structure of the absorption band of nearly stoichiometric crystals consisted of three sub-bands with slightly different peak position, and their relative height change with Li/Nb ratios. The OH− absorption band in heavily Mg-doped crystal had a structure consisting of two peaks, and the shift of peak position to shorter wavelength was about 54 cm−1. On the basis of the crystal structure and the model of the defect structure of the LiNbO3 crystal suggested by Abrahams and Smyth,1–2 these observations have been discussed with different structure argument: stoichiometric, congruent and Mg-doped crystals, respectively. The shift of the peak position of the OH− absorption band in heavily Mg-doped crystal to shorter wavelength is suggested to be caused by the Mg2+ ions getting into sites when the Mg-doping level was higher than the threshold level in Mg-doped ...