A new approach to intrinsic and extrinsic defect sub-systems, which considered them to be a single integrated functional system, was developed for complex oxides. The strong interrelationship of these sub-systems became especially apparent when the concentrations of the 2 defect classes were comparable. A new parameter, which reflected the total intrinsic defect concentration, was introduced in order to determine the degree of crystal imperfection. The need to have at least 2 calibrated sample crystals, one congruent and one regularly ordered, was confirmed. The accuracy to which the parameter could be determined served as a criterion for comparing different methods of crystal characterisation. This heuristic generalization of the concept of a mutual correlation of the whole defect system and the material was possible as a result of experimental and theoretical studies of large numbers of LiNbO3 crystals. The spectra of electron paramagnetic resonance, nuclear magnetic resonance, electron nuclear double resonance and other properties of crystals with various compositions and impurities were analyzed.

Interrelation of Intrinsic and Extrinsic Defects - Congruent, Stoichiometric and Regularly Ordered Lithium Niobate. G.Malovichko, V.Grachev, O.Schirmer: Applied Physics B, 1999, 68[5], 785-93