Nuclear magnetic resonance study of atomic motion in the mixed Borohydride-amide Na2(BH4)(NH2)

Alexei V. Soloninin, Olga A. Babanova, Evgeny Y. Medvedev, Alexander V. Skripov, Motoaki Matsuo, Shin Ichi Orimo

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15 Citations (Scopus)

Abstract

To study the reorientational motion of the anions and the translational diffusion of Na+ cations in the mixed borohydride-amide Na 2(BH4)(NH2) showing fast-ion conduction, we have measured the 1H, 11B, and 23Na NMR spectra and spin-lattice relaxation rates in this compound over broad ranges of temperature (6-480 K) and the resonance frequency (14-132.3 MHz). At low temperatures (T < 190 K), the proton spin-lattice relaxation rate is governed by fast reorientations of BH4 groups. This reorientational process can be satisfactorily described in terms of a Gaussian distribution of the activation energies with the average Ea value of 74 ± 7 meV. Above 250 K, the measured proton spin-lattice relaxation rate originates from two other (slower) reorientational jump processes characterized by the average activation energies of 340 ± 9 meV and 559 ± 7 meV. The 23Na spin-lattice relaxation data in the high-temperature region are governed by translational diffusion of Na+ ions, which is consistent with high Na-ion conductivity in Na2(BH4)(NH2).

Original languageEnglish
Pages (from-to)14805-14812
Number of pages8
JournalJournal of Physical Chemistry C
Volume118
Issue number27
DOIs
Publication statusPublished - 2014 Jul 10

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Energy(all)
  • Physical and Theoretical Chemistry
  • Surfaces, Coatings and Films

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