Abstract
There are many structure types of niobates, of which KNbO3 (KN) with perovskite structure, Ba2NaNb5O15 (BNN) with tungsten-bronze structure and LiNbO3 (LN) are well-known NLO materials. It has been demonstrated that the deformed NbO6 coordination octahedra in these materials are the basic structural units for the production of NLO effects.1 The NbO6 octahedra are deformed in different ways: i.e., a threefold axis deformation in LN, a twofold axis deformation in KN, and a mainly fourfold axis deformation in BNN. In the light of the anionic group theory of NLO effect,2 of the three types of NbO6 octahedron deformation, the one along a fourfold axis is the most advantageous. A broad survey of niobates containing deformed NbO6 octahedra led to the discovery of new NLO material ZnLiNbO4 (ZLN). ZLN possesses a spinel structure wherein the basic structural unit NbO6 octahedron is deformed tetragonally. Although McCarthy and Keramidas reported its point group as 422,3 which implies that ZnLiNbO4 exhibits no SHG effect, we observed large SHG effect in this compound.
© 1995 IEEE
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