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An Estimation of Nonlinear Optical Properties of Lithium Niobate Family Ferroelectrics by the Chemical Bond Model

Starting from the crystallographic structure of lithium niobate family ferroelectrics, the chemical bond model of solids is employed to quantitatively analyze the chemical bonding structure and property of constituent atoms in the crystallographic frame. On the basis of the crystal structure and related structure-property relationship of such a crystal family, nonlinear optical properties of crystals in this family are quantitatively estimated. A Nb-site-dependent and Li-site-sensitive model is further proposed to successfully describe various chem-physical properties of lithium niobate family crystals. Different models proposed by previous authors for the lithium niobate crystal structure and related defect structures are also discussed in this work.