A series of LiNbO3:Fe:Mg:Zr single crystals with various Li/Nb ratios in the melt were grown by the Czochralski method in the air. The ultraviolet-visible and infrared transmittance spectra were measured to investigate the defect structures of these crystals. A new vibration peak of 3502 cm(-1) was observed in infrared transmittance spectra. The sequence of substitution was concluded according to the spectroscopic characterization. The light-induced scattering of LiNbO3:Fe:Mg:Zr crystals was characterized quantitatively via the incident exposure energy, and the relationship between the defect structures and light-induced scattering was discussed. (C) 2011 Elsevier B.V. All rights reserved.