IR observation on O–D vibration in LiNbO3 and LiTaO3 single crystal irradiated by 3 keV

The behavior and existence states of deuterium irradiated into LiNbO3 and LiTaO3 single crystals were studied by in situ FT-IR observations on multiple O–D vibration peaks and by TDS on the desorption behavior of deuterium. Two O–D vibration peaks were observed in both LiNbO3 and LiTaO3, one at 2610–2615 cm−1 and the other at 2560–2570 cm−1. The former O–D vibration was attributed to –OD− affected by Nb defect in LiNbO3 or Ta defect in LiTaO3. For attribution of the latter O–D vibration, two candidates remained, –OD− affected by Li vacancy and –OD− of interstitial D+. By heating after the ion irradiation, the irradiated deuterium was mainly desorbed as hydrogen molecular forms (D2 and HD). The –OD− affected by Nb defect in LiNbO3 or Ta defect in LiTaO3 had a higher desorption temperature than the other –OD−s. The two materials showed similar results in the existence states and the desorption behavior of irradiated D+, although some differences were observed due to more formation of Nb defect in LiNbO3 than Ta defect in LiTaO3 by displacement. It was indicated that the release temperature of hydrogen isotopes is heightened by the influence of M defect in ternary lithium oxides (LixMOy).