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DOI	10.1073/pnas.2021810118
	Fluid-like elastic response of superionic NH3 in Uranus and Neptune
	Kimura T.; Murakami M.
发表日期	2021
ISSN	00278424
卷号	118 期号:14
英文摘要	Nondipolar magnetic fields exhibited at Uranus and Neptune may be derived from a unique geometry of their icy mantle with a thin convective layer on top of a stratified nonconvective layer. The presence of superionic H2O and NH3 has been thought as an explanation to stabilize such nonconvective regions. However, a lack of experimental data on the physical properties of those superionic phases has prevented the clarification of this matter. Here, our Brillouin measurements for NH3 show a two-stage reduction in longitudinal wave velocity (Vp) by ∼9% and ∼20% relative to the molecular solid in the temperature range of 1,500 K and 2,000 K above 47 GPa. While the first Vp reduction observed at the boundary to the superionic α phase was most likely due to the onset of the hydrogen diffusion, the further one was likely attributed to the transition to another superionic phase, denoted γ phase, exhibiting the higher diffusivity. The reduction rate of Vp in the superionic γ phase, comparable to that of the liquid, implies that this phase elastically behaves almost like a liquid. Our measurements show that superionic NH3 becomes convective and cannot contribute to the internal stratification. © 2021 National Academy of Sciences. All rights reserved.
英文关键词	Ammonia; Brillouin spectroscopy; Elastic property; Superionic state; Uranus and Neptune
语种	英语
来源期刊	Proceedings of the National Academy of Sciences of the United States of America
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/179981
作者单位	Department of Earth Sciences, Eidgenössische Technische Hochschule (ETH) Zürich, Zürich, 8092, Switzerland; Department of Earth and Planetary Materials Science, Graduate School of Science, Tohoku University, Miyagi, 980-8578, Japan; Geodynamics Research Center, Ehime University, Ehime, 790-8577, Japan
推荐引用方式 GB/T 7714	Kimura T.,Murakami M.. Fluid-like elastic response of superionic NH3 in Uranus and Neptune[J],2021,118(14).
APA	Kimura T.,&Murakami M..(2021).Fluid-like elastic response of superionic NH3 in Uranus and Neptune.Proceedings of the National Academy of Sciences of the United States of America,118(14).
MLA	Kimura T.,et al."Fluid-like elastic response of superionic NH3 in Uranus and Neptune".Proceedings of the National Academy of Sciences of the United States of America 118.14(2021).