The Spectrum Characterization of Non-Stoichiometry Potassium Lithium Niobate Crystals
WAN You-bao1, 2,YUAN Guo-xiang2,WU Yu-rong2,YANG Pei-zhi3,XIN San-fa2,ZHU Hai-bin2,HUANG Xue-jun2,YANG Hui1
1. Institution of Inorganic Material, College of Material and Biology, Zhejiang University, Hangzhou 310027, China 2. Institution of Advanced Material, Jiaxin University, Jiaxing 314000, China 3. Kunming Institute for Physics, Kunming 650223, China
Abstract：A batch of potassium lithium niobate(KLN) crystals with different compositions were grown by using TSSG technique. Samples with three different compositions were well polished. By using near infrared cw: Ti-sapphire laser，their Second Harmonic Generation (SHG) properties were investigated. The results showed that the SHG effect is related to the composition of the samples, and their frequency-doubling efficiency enhanced with the raise of Li ions content in the crystal. By using infrared Raman technique, the properties of nonlinear lattice vibration of thee samples were investigated, and the character of Raman spectrum were analyzed, as well the effect of composition on the SHG properties were discussed. The analysis results showed the striking effects of Li content for these Raman peaks. For KLN sample with small Li content, the three character peaks belonged to [NbO6]7- octahedron show simple peak. With the raise of Li content in crystal, the peaks belonged to ν2 mode were partly split, and the peak belongs to ν5 mode was broadened. When the Li content approach to the chemical composition KLN crystal, and the structure of [NbO6]7-octahedron is almost to be disorganized, the peaks belonged to ν5 mode were split, and the peaks belonged to ν1 mode and ν2 mode were partly split also, with more distinct weak peaks in the wavelength range of 100-400 cm-1. These effects were caused by the raise of Li content, which leads to the severer aberrance of [NbO6]7-octahedron in KLN crystal, and disturbing the lattice vibration of the octahedron. This phenomenon is agreed with the nonlinear properties of potassium lithium niobate crystal.
[1] Ouwerker M. Adv. Mat., 1991, 3(7/8): 339. [2] Reid J J E. Appl. Phys. Lett., 1993, 62(1): 19. [3] Wan Youbao, Guo Xuguang, Chen Jing, et al. J. Cryst. Growth., 2002, 235(1-4): 248. [4] Scott B A, Giess E A, Olson B L. Mat. Res. Bull., 1970, 5: 47. [5] Roon D H, Shur C C, Fukuda T. Cryst Res. Technol., 1998, 33(1): 59. [6] Song Y T, Zhao D F, Liu H B. J. Cryst Growth., 1998, 194: 379. [7] Fortin W, Kugel G E, Rytz D. Ferroelectrics., 1997, 202: 183. [8] WANG Rong, FENG Min, WU Wei-hong, et al(王 荣, 冯 敏, 吴卫红, 等). Spectroscopy and Spectral Analysis(光谱学与光谱分析), 2005, 25(9): 1422. [9] Abrahams S C, Jaminson P B. Chem. Phys., 1968, 48(11): 5048.
