Photorefractive properties of LiNbO3 : Zn crystals related to the defect structure

LiNbO3:Zn single crystals and powders were studied by precise X-ray diffrac tion methods. Structural refinement yielded new models of the intrinsic def ect structure valid for different Zn concentration ranges. For concentratio ns up to 7 at. % in the crystal, Zn ions incorporate onto Li sites; at high er concentrations Zn ions are found on both Li and Nb sites. Photorefractiv e properties of LiNbO3:Zn are discussed in the context of the deduced defec t models. A smooth increase in the photoconductivity up to 7 at. % Zn is ac counted for by a decrease of Nb antisites. Steeper growth of the photocondu ctivity at higher Zn concentrations is related to vanishing Li vacancies.