Proton-exchanged OH^- absorption spectra of highly Zn-doped LiNbO₃ with and without polarization inversion

The proton-exchanged OH^- absorption spectra of congruent and 8.1 mol % Zn-doped LiNbO₃ single crystals with and without polarization inversion are presented. The variation in the proton-exchanged OH^- spectra for the congruent sample is not affected by polarization inversion. This result confirms the Li-vacancy model. However, the highly doped sample shows stronger increase in intensities with polarization inversion. In our investigation, highly negative charge vacancy model confirms with proton-exchanged OH^- absorption spectra and domain inversion etching experiment. Finally, we demonstrated the polarization inversion mechanism with these two samples based on extended x-ray-absorption fine structure experimental results.