A series of near-stoichiometric Zn:LiNbO3 (Zn:NSLN) crystals were grown by the top seed solution growth (TSSG) method using KO as flux. Defect structures and Zn2+ occupation mechanism were analyzed and discussed by X-ray powder diffraction (XRD), differential thermal analysis (DTA), ultraviolet-visible (UV) absorption and infrared (IR) spectrum measurement. Moreover, we also found that the threshold concentration of ZnO in NSLN were between 2 and 3 mol%. (C) 2004 Elsevier B.V. All rights reserved.