Authors: Rawn, Claudia J.; Birnie, Dunbar P. III
Source: Ferroelectrics 153 (1994)  291-296

Abstract: Iron impurities play an important role in photorefractive optical damage in lithium niobate crystals. Yet, in spite of its importance, the plentiful studies of iron incorporation into the lattice still leave no quantitative model of the substitution site or the appropriate chemical incorporation reaction. X-ray powder diffraction studies have been used to examine the solid solution changes in the lattice constants. Both the a-lattice constant and volume were found to decrease with increasing Fe₂O₃ content while the c-lattice constant increased with increasing Fe₂O₃ content. These changes were associated specifically with an iron oxide solution mechanism where iron substitutes onto both lithium and niobium lattice sites. The defect chemical reactions used to describe this solid solution process are discussed.