Proton dynamics in antiferroelectric CsH3(SeO3)2 single crystal investigated by 1H NMR measurements

• Published in: Current applied physics 2020, 20(5), , pp.673-679
• Main Authors: Ndiaye, B., Kim, Yonghwan, Lee, Moohee, Lim, Ae Ran
• Format: Article
• Language: English
• Subjects: Activation energy of proton motion; Antiferroelectric phase transition; CsH3(SeO3)2; Proton dynamics by 1H NMR; Spin-lattice relaxation time T1; 물리학
• ISSN: 1567-1739; 1878-1675
• DOI: 10.1016/j.cap.2020.02.014

1H nuclear magnetic resonance (NMR) measurements have been performed to study the proton dynamics associated with the antiferroelectric transition of a hydrogen-bonded single crystal of CsH3(SeO3)2. Herein, 1H NMR spectrum, shift, linewidth, and spin-lattice relaxation rate 1/T1 are measured in the temperature range of 80–296 K with the c-axis parallel to a magnetic field of ~4.85 T. The spectrum exhibits a composite structure with two narrow peaks at 296 K; at a low temperature, this structure evolves into a single broad shape with three humps. This complex shape and evolution are deconvoluted into five or six components based on the number of inequivalent and disordered hydrogen sites. By estimating the chemical shift and linewidth for each proton site, we identify all peaks. The spin-lattice relaxation recovery exhibits a double-exponential behavior with two relaxation times, short T1S and extremely large T1L. Both T1S and T1L follow Arrhenius behavior. From the respective 1/T1(T), the activation energies for proton motion are measured to be small: 1.16 ± 0.1 and 0.83 ± 0.06 kJ/mol for T1S and T1L, respectively. While the static NMR data, chemical shift and linewidth, show no evidence for the transition, the dynamic data 1/T1L highlights a clear increase across TN = 145 K, which is possibly a signature of the transition. •1H NMR spectrum, shift, linewidth, and T1 were measured to study proton dynamics along the antiferroelectric transition.•The spectrum showed a composite structure which was deconvoluted into five or six peaks based on the number of proton sites.•By estimating the chemical shift and linewidth, we can identify all the peaks from the six proton sites.•From 1/T1S and 1/T1L vs. 1/T, the activation energies of proton motion are found to be respectively 1.16 and 0.83 kJ/mol.•Although NMR shift and linewidth data show no evidence, 1/T1L highlights a clear increase as a signature across TN.