Acta Chimica Sinica ›› 2022, Vol. 80 ›› Issue (5): 633-639.DOI: 10.6023/A22010020 Previous Articles     Next Articles

Special Issue: 中国科学院青年创新促进会合辑

Article

Rb2MGe3S8 (M=Zn, Cd): [MGe3S8]2–单元构型变换导致化合物从中心到非心的转变

柴贤丹a,b, 陈文发b, 闫秋楠b, 刘彬文b, 姜小明b,*(), 郭国聪b,*()   

  1. a 福建师范大学化学与材料学院 福州 350007
    b 中国科学院福建物质结构研究所 结构化学国家重点实验室 福州 350608
  • 投稿日期:2022-01-12 发布日期:2022-02-17
  • 通讯作者: 姜小明, 郭国聪
  • 作者简介:
    庆祝中国科学院青年创新促进会十年华诞.
  • 基金资助:
    国家自然科学基金(22075283); 国家自然科学基金(22175172); 国家自然科学基金(92161125); 中国科学院青年创新促进会(2020303); 中国科学院青年创新促进会(2021300)

Rb2MGe3S8 (M=Zn, Cd): Non-Centrosymmetry Transformation Led by Structure Change of [MGe3S8]2- Unit

Xiandan Chaia,b, Wenfa Chenb, Qiunan Yanb, Binwen Liub, Xiaoming Jiangb(), Guocong Guob()   

  1. a School of Chemistry and Materials, Fujian Normal University, Fuzhou, 350007
    b State Key Laboratory of Structural Chemistry, Fujian Institute ofResearch on the Structure of Matter, Chinese Academy of Sciences, Fuzhou, 350608
  • Received:2022-01-12 Published:2022-02-17
  • Contact: Xiaoming Jiang, Guocong Guo
  • About author:
    Dedicated to the 10th anniversary of the Youth Innovation Promotion Association, CAS.
  • Supported by:
    National Natural Science Foundation of China(22075283); National Natural Science Foundation of China(22175172); National Natural Science Foundation of China(92161125); Youth Innovation Promotion Association of Chinese Academy of Sciences(2020303); Youth Innovation Promotion Association of Chinese Academy of Sciences(2021300)

Infrared nonlinear (IR NLO) optical crystals have an essential position in military and civilian fields because of their ability to convert lasers from near infrared (NIR) to mid/far infrared (MIR/FIR). In this work, two alkali-metal chalcogenides, Rb2MGe3S8 [M=Zn (1), Cd (2)], were successfully synthesized by high-temperature solid-state reactions. Both compounds feature a two-dimensional layered structure and have a large optical band-gap, the experimental band-gap of 1 and 2 are 3.24 eV and 3.16 eV, respectively. Compound 1 belongs to the centrosymmetric group P-1, while 2 belongs to the non-centrosymmetric space group P2(1)2(1)2(1) and exhibits obvious NLO effect, which is comparable to that of KH2PO4 (KDP) (@1064 nm) at the particle size of 50~75 μm. Particle-size dependent NLO response measurements indicated that 2 is non-phase-matchable. Compound 2 exhibits a high laser-induced damage threshold of 16.6×AGS at 1064 nm. Through the analysis of the crystal structures of these two compounds, the reason why their formulas have the same stoichiometric ratio but symmetries are different is the structure change of basic building unit [MGe3S8]2– in 1 and 2. All M atoms in both compounds are coordinated by four S atoms to form MS4 tetrahedra. In each [CdGe3S8]2– unit of 2, three S atoms bonded to the Cd atom are also bonded to all Ge atoms in that unit, that is to say, each CdS4 tetrahedron is connected to the other three GeS4 tetrahedra by sharing S vertices. Unlike the coordination manner in the [CdGe3S8]2– unit of 2, there are only two S atoms bonded to both Zn and Ge atoms in [ZnGe3S8]2– unit of 1. This structure change of [MGe3S8]2– unit eventually led to the non-centrosymmetric transformation. What’s more, to get insight into the origin of NLO effect of 2, theoretical calculations of electronic band structure and NLO susceptibility were performed based on density functional theory.

Key words: chalcogenides, nonlinear optical, non-centrosymmetric transformation, theoretical calculation