An infrared absorption band caused by H+implantation in LiNbO3crystals

Abstract
A new infrared absorption band at a wavenumber of about 3545 cm-1 has been observed in LiNbO3 crystals implanted with energetic H+ ions. It is found that the peak wavenumber of this band seems to be independent of the stoichiometry, dopant species and doping level in the investigated samples. The band, polarized perpendicular to the c axis, disappears after the sample was annealed in air at 500 degrees C for 0.5 h. The new absorption band is interpreted as a distributed OH stretching vibration in a H+-implanted LiNbO3. The displacement of Nb5+ ions from their regular sites (which was caused by the ion implantation) may expand the oxygen triangle to result in a longer O-O bond this can explain the higher wavenumber of the OH band in the H+-implanted LiNbO3.