Optical absorption, electron spin resonance (ESR), thermoluminescence, and x‐ray‐
induced luminescence techniques have been used to characterize point defects in LiNbO3.
A series of crystals with different magnesium‐doping levels and Li/Nb ratios were
investigated, and the defects were introduced either by x‐ray irradiation at low temperatures
(10–85 K) or by reduction at high temperature in a vacuum. The samples may be classified
into two groups, according to their response to radiation and reduction. A threshold (ie, a …