新型紫外非线性光学晶体KNa_5Ca_5(CO_3)_8的合成、表征及性能的研究  

Synthesis, Characterization and Property of a New UV Nonlinear Optical Crystal KNa_5Ca_5(CO_3)_8

作　　者：陈巧玲 罗敏[2] 林晨升[2] CHEN Qiao-Ling;LUO Min;LIN Chen-Sheng(College of Mathematics and Physics, Fujian University of Technology, Fuzhou 350108, China;Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China)

机构地区：[1]福建工程学院数理学院,福州350108 [2]中国科学院福建物质结构研究所,福州350002

出　　处：《无机材料学报》2018年第6期667-672,共6页Journal of Inorganic Materials

摘　　要：采用水热法合成出一种新型碳酸盐非线性光学晶体材料KNa_5Ca_5(CO_3)_8,该晶体属于六方晶系,空间群为P63mc,晶胞参数为a=b=1.00786(4)nm,c=1.26256(8)nm,Z=2。其晶体结构可以看作是由站立的[CO_3]基团连接相邻的两个[CaCO_3]∞层,从而沿[010]方向形成了四种不同类型的孔洞,在这些孔洞中填充着K、Na和[Na0.67Ca0.33]原子。KNa_5Ca_5(CO_3)_8晶体的粉末倍频效应为KDP的1.2倍,且能够在可见光区实现相位匹配。紫外-可见-近红外漫反射光谱测试结果表明其晶体具有较大的光学带隙,大概为5.95 e V,是具有潜在应用前景的紫外非线性光学晶体材料。此外,第一性原理的计算结果表明,晶体的非线性系数主要来源于CO_3基团。A new carbonate nonlinear optical （NLO） material, KNa5Ca5（CO3）8, was successfully synthesized by mild hydrothermal method. It crystallizes in hexagonal space group （P63mc） with lattice parameters a=b=1.00786（4） and c=1.26256（8） nm （Z=2）. Structure of KNa5Ca5（CO3）8 can be described as standing-on-edge [CO3] groups connecting the adjacent infinite [CaCO3]∞ layers in the a-b plane to construct a framework with four types of channels running parallel to [010]. K, Na and [Na0.67Ca0.33] atoms reside in the tunnels. In the structure, the flat-lying [CO3] groups in two successive layers present an opposite orientation. This arrangement is negative for NLO susceptibilities. The macroscopic of SHG effects, however, originated from the standing-on-edge [CO3] group along c axis. It is regrettable that the standing-on-edge [C303] and [C403] groups are almost arranged oppositely to the c direction, which weakens the SHG contribution from the standing-on-edge [CO3] groups. Measurement of second harmonic generation （SHG） by the method adapted from Kurtz and Perry indicates that the compound is phase-matchable in visible region and ex- hibit moderate SHG response about 1.2 times higher than that of KH2PO4. In addition, UV-Vis-NIR diffuse reflectance spectral measurements indicate that KNa5Ca5（CO3）8 has a large optical gap about 5.95 eV. Moreover, first-principles electronic structure calculations show that the CO3 groups play an important role in the total SHG response. Therefore, our data suggests that the new compound as NLO material may have potential applications in the UV region.

关 键 词：紫外 碳酸盐 非线性光学晶体 晶体生长 

分 类 号：TQ174[化学工程—陶瓷工业]