The UV absorption edge and IR spectrum of the OH ion vibration have systematically been measured in LiNbO3 samples for a wide composition and Mg concentration range. The Mg content (0-9 mol %) of the crystals with congruent, stoichiometric and an intermediate composition has been determined by atomic absorption spectroscopy. At a Mg threshold concentration, depending on the Li/Nb ratio, the vibrational frequency of the hydroxyl ions moves abruptly to higher energies, while the shift of the UV-edge changes its direction. Above the threshold value there is an approx. square root dependence for the OH - frequency and a linear dependence for the UV-edge as a function of Mg concentration. It was shown that both NbLi and Mg ions determine the UV-edge of LiNbO3́:Mg.
ASJC Scopus subject areas
- Condensed Matter Physics