An infrared absorption band caused by H⁺implantation in LiNbO₃crystals

A new infrared absorption band at a wavenumber of about 3545 cm -1 has been observed in LiNbO 3 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 LiNbO 3 . The displacement of Nb 5+ 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 LiNbO 3 .