Nuclear magnetic resonance study of anion and cation dynamics in CsSiH3
JOURNAL OF ALLOYS AND COMPOUNDS(2019)
摘要
In order to study the dynamical properties of cesium silanide CsSiH3, we have measured the H-1 and Cs-133 nuclear magnetic resonance (NMR) spectra and spin-lattice relaxation rates in this compound over the temperature range of 5-354 K. The results of the H-1 NMR measurements indicate that [SiH3](-) anions in CsSiH3 retain unusually high reorientational mobility down to low temperatures. In particular, a significant narrowing of the proton NMR spectrum due to [SiH3](-) reorientations is observed in the range similar to 10-14 K. The order-disorder (beta ->alpha) phase transition accompanied by the strong acceleration of [SiH3](-) reorientations and by the change in the reorientational mechanism is observed above 200 K; according to the H-1 spin-lattice relaxation data, this transition appears to be gradual. For the high-temperature disordered alpha-phase, the activation energy for [SiH3]( )reorientations is found to be 41(4) meV. The Cs-133 NMR results are consistent with the onset of diffusive motion of Cs+ cations at the frequency scale of similar to 10(4) s(-1) above 300 K. (C) 2018 Elsevier B.V. All rights reserved.
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关键词
Energy storage materials,Diffusion,Nuclear resonances
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