EPR and Optical Absorption Investigations of Photochromic Effect in Nearly Stoichiometric LiNbO3:Fe
EPR and optical absorption measurements have been performed on nearly stoichiometric lithium niobate single crystals with iron in traces and in 0.1% molar nominal amount. Thermal treatments in reducing atmosphere allowed to obtain samples with different Fe2+/Fe3+ ratios. The Fe2+/Fe3+ dynamic has been observed by irradiating the samples with UV and visible light in the temperature range 4-300 K: the photochromic effect resulted to be more evident in the strongly reduced crystals. A simple model to explain the photochromic behavior in nearly stoichiometric LiNbO3:Fe is proposed.
Paula Maria Vilarinho
M. C. Mozzati et al., "EPR and Optical Absorption Investigations of Photochromic Effect in Nearly Stoichiometric LiNbO3:Fe", Materials Science Forum, Vols. 514-516, pp. 152-155, 2006