化学学报 ›› 2022, Vol. 80 ›› Issue (5): 633-639.DOI: 10.6023/A22010020 上一篇    下一篇

研究论文

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)

在本工作中, 利用高温固相法成功合成了两个碱金属硫属化合物Rb2MGe3S8 [M=Zn (1), Cd (2)]. 化合物1, 2都为二维层状结构且均具备大的光学带隙, 化合物12的实验带隙分别为3.24和3.16 eV. 化合物1属于P-1中心对称群, 化合物2属于非心P2(1)2(1)2(1)空间群且具有一定的非线性光学(NLO)效应, 在粒径为50~75 μm时与KH2PO4 (KDP)相当(@1064 nm). 化合物2的激光损伤阈值为AgGaS2的16.6倍. 化合物1, 2的分子式化学计量比相同但展示不同的对称性, 通过分析它们的晶体结构发现, 其基本构造单元[MGe3S8]2–在两化合物中构型的不同导致化合物12对称性发生中心到非心的转变. 为了深入了解化合物2的NLO效应的起源, 基于密度泛函理论对其进行了电子能带结构和NLO极化率的理论计算.

关键词: 硫属化合物, 非线性光学, 中心到非心转变, 理论计算

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