Combination bands of libration+vibration of OH/OD centres in ABO3 crystals

摘要: The presence of hydrogen (deuterium) defects in oxide ABO3 crystals is revealed by a characteristic OH (OD) stretching vibration near 3500 cm-1 (2600 cm-1). Low-frequency librational modes have not been reported so far for these crystals. However, we found number (LiNbO3, LiTaO3, SrTiO3 and KTaO3) weak high-energy sidebands to the with positions shifted about 950 700 OD from vibrational band position. bandshape new OH/OD absorption bands similar corresponding polarization general different reflects more properties three-dimensional oscillator. While vibrations LiNbO3 LiTaO3 are completely polarized perpendicular ferroelectric z-axis, libration+vibration combination exhibit both crystal systems an intensity ratio I/sub ////Iperpendicular approximately 0.55 0.75 respect z-axis. These ratios support identification as also detected higher transitions proton- (deuteron-) exchanged LiNbO3. In first approximation energetic observed can be well described simple oscillator model libration. directly proportional (or concentration) H D) centres.