A comparative study was made of single crystals, which had congruent and near-stoichiometric compositions, by using hyperfine interactions and ion beam techniques. The data showed that the structure of the congruent material could not be completely described by models which assumed only the presence of vacancies and Nb antisites. Additional disorder at both the Li and Nb sites had to be considered. The additional defects were cation stacking inversions, in which the cation sequence coincided locally with that of ilmenite. It was suggested that these stacking inversions were associated with the Nb antisites that were necessary for charge compensation in Li-deficient material.

Structural Defects in Congruent and Near-Stoichiometric LiNbO3. J.G.Marques, A.Kling, J.C.Soares, M.F.Da Silva, R.Vianden, K.Polgard, E.Dieguez, F.Agullo-Lopez: Radiation Effects and Defects in Solids, 1999, 150[1-4], 625-8