波谱学杂志 ›› 2020, Vol. 37 ›› Issue (1): 76-85.doi: 10.11938/cjmr20192755

• 研究论文 • 上一篇    下一篇

通过超宽139La固体核磁共振波谱研究层状La(OH)2NO3

冯宗静1, 杜亚平1, 罗锋2, 徐骏1   

  1. 1. 南开大学 材料科学与工程学院/国家新材料研究院, 天津市稀土材料与应用重点实验室, 稀土与无机功能材料研究中心, 天津 300350;
    2. IMDEA Nanoscience, Faraday 9, Ciudad Universitaria de Cantoblanco, Madrid 28049
  • 收稿日期:2019-06-05 出版日期:2020-03-05 发布日期:2019-09-16
  • 通讯作者: 杜亚平,Tel:18621310123,E-mail:ypdu@nankai.edu.cn;徐骏,Tel:18522736531,E-mail:junxu@nankai.edu.cn. E-mail:ypdu@nankai.edu.cn;junxu@nankai.edu.cn
  • 基金资助:
    国家自然科学基金青年基金资助项目(21904071)

An Ultrawide-Line 139La Solid-State NMR Investigation of Layered La(OH)2NO3

FENG Zong-jing1, DU Ya-ping1, LUO Feng2, XU Jun1   

  1. 1. Center for Rare Earth and Inorganic Functional Materials, Tianjin Key Laboratory for Rare Earth Materials and Applications, School of Materials Science and Engineering & National Institute for Advanced Materials, Nankai University, Tianjin 300350, China;
    2. IMDEA Nanoscience, Faraday 9, Ciudad Universitaria de Cantoblanco, Madrid 28049, Spain
  • Received:2019-06-05 Online:2020-03-05 Published:2019-09-16

摘要: 层状稀土氢氧化物是一类新型的稀土功能材料,本文采用固体核磁共振(SSNMR)方法研究了同时具备离子交换能力和非线性光学特性的层状La(OH)2NO3化合物,探讨了通过四极核CPMG(QCPMG)脉冲序列和变频谱图采集获取超宽139La SSNMR谱图的方法,并描述了适用于此类实验的滤波方程和谱图重建方法.重建谱图同时包含四极核中心跃迁和卫星跃迁信息,本文使用QUEST软件对超宽139La NMR谱图进行了模拟,获取的四极耦合常数CQ和非对称因子ηQ均与CASTEP密度泛函理论计算值高度吻合.SSNMR实验结果证实层状La(OH)2NO3化合物属于非中心对称结构(P21),解决了对其结构长期以来存在的争论.

关键词: 139La固体核磁共振, 超宽核磁共振波谱, 四极核, QCPMG脉冲, 层状化合物

Abstract: Layered rare earth hydroxides are new classes of functional materials. In this study, a layered La(OH)2NO3 compound having both ion-exchange capacity and non-linear optical property was studied by solid-state nuclear magnetic resonance (SSNMR) spectroscopy. The quadrupolar Carr-Purcell-Meiboom-Gill sequence (QCPMG) was used to acquire 139La SSNMR sub-spectra with variable offsets, from which the ultrawide-line spectrum was reconstructed by co-addition after applying a filtering function. The ultrawide-line spectrum consisted of both center and satellite transition line shapes, which were also simulated with the QUEST software. The 139La CQ and ηQ values measured by SSNMR experiments agreed well with those calculated with the Cambridge Sequential Total Energy Package (CASTEP). The 139La SSNMR results unambiguously indicated that the layered La(OH)2NO3 compound studied belongs to a non-centrosymmetric space group of P21.

Key words: 139La solid-state NMR, ultrawide-line NMR spectrum, quadrupole nucleus, QCPMG pulse sequence, layered compounds

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