Journal of Inorganic Materials ›› 2018, Vol. 33 ›› Issue (6): 667-672.DOI: 10.15541/jim20170335

• Orginal Article • Previous Articles     Next Articles

Synthesis, Characterization and Property of a New UV Nonlinear Optical Crystal KNa5Ca5(CO3)8

CHEN Qiao-Ling1, LUO Min2, LIN Chen-Sheng2   

  1. 1. College of Mathematics and Physics, Fujian University of Technology, Fuzhou 350108, China;
    2. Key Laboratory of Optoelectronic Materials Chemistry and Physics, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China;
  • Received:2017-07-17 Revised:2017-08-24 Online:2018-06-20 Published:2018-05-24

Abstract:

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 ?at-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 [C3O3] and [C4O3] 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 exhibit 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.

 

Key words: UV, carbonates, nonlinear optical crystal, crystal growth

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