非线性光学晶体δ-LiZnPO_4的制备、结构及光学性能

研究了LiF为助熔剂体系下的δ-LiZnPO_4的结晶特性,通过自发结晶得到了尺寸为1~3 mm的透明块状δ-LiZnPO_4和Li_4Zn(PO_4)_2共晶体,通过PXRD衍射分析和元素分析确定了共晶体的相组成,并对从共晶体中分离出的δ-LiZnPO_4晶体结构进行了分析。结果表明:δ-LiZnPO_4晶体具有非中心对称结构,属于正交晶系,空间群为Pna2_1,晶格常数a=1.00085 nm,b=0.49390 nm,c=0.66545 nm,Z=4;δ-LiZnPO_4是由PO_4、ZnO_4和LiO_4四面体构筑成的具有类似ABW型分子筛结构的化合物。采用水热法制备了尺寸约为10μm的纯相透明的δ-LiZnPO_4晶体。粉末倍频测试表明,δ-LiZnPO_4晶体倍频效应约为KDP的1.7倍,紫外截止边约为218 nm,是一种有潜在应用价值的紫外非线性光学晶体。

Synthesis,Structure Characterization and Optical Property of Nonlinear Optical Crystal δ-LiZnPO4

Crystalline characteristic of δ-LiZnPO4 was studied under using LiF as flux system.Transparent eutectic crystallization of δ-LiZnPO4 and Li4Zn(PO4)2 with size of 1-3 mm was obtained by spontaneous crystallization method.Eutectic phase composition was determined via X-ray diffraction and element analysis, and structure of δ-LiZnPO4 crystal separated from the eutectic crystal was analyzed.The results show that the δ-LiZnPO4 crystals have a non-centerosymmetrical structure, belong to the orthogonal crystal system, space group Pna21 with lattice parameter a=1.00085 nm, b=0.93900 nm, c=0.66545 nm, Z=4.Structure analysis confirms that the crystal consists of PO4, ZnO4 and LiO4 tetrahedron to form a zeolite structure type of ABW.The transparent pure phase δ-LiZnPO4 single crystal with size of about 10 μm was also synthesized by hydrothermal method.Powder second harmonic generation (SHG) tests show that the powder SHG effect of δ-LiZnPO4 crystal is about 1.7 times of KDP and the ultraviolet(UV) cut-off wavelength of δ-LiZnPO4 crystal is 218 nm, which indicate that δ-LiZnPO4 crystal is a promising nonlinear optical crystal in the UV region.