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MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K

Fat'yanov, Oleg V. and Asimow, P. D. (2014) MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K. Journal of Physics: Conference Series, 500 (6). Art. No. 062003. ISSN 1742-6596. https://resolver.caltech.edu/CaltechAUTHORS:20140729-082224529

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Abstract

Continuing our effort to obtain experimental constraints on the melting curve of MgO at 100-200 GPa, we extended our target preheating capability to 2300 K. Our new Mo capsule design holds a long MgO crystal in a controlled thermal gradient until impact by a Ta flyer launched at up to 7.5 km/s on the Caltech two-stage light-gas gun. Radiative shock temperatures and rarefaction overtake times were measured simultaneously by a 6-channel VIS/NIR pyrometer with 3 ns time resolution. The majority of our experiments showed smooth monotonic increases in MgO sound speed and shock temperature with pressure from 197 to 243 GPa. The measured temperatures as well as the slopes of the pressure dependences for both temperature and sound speed were in good agreement with those calculated numerically for the solid phase at our peak shock compression conditions. Most observed sound speeds, however, were ~800 m/s higher than those predicted by the model. A single unconfirmed data point at 239 GPa showed anomalously low temperature and sound speed, which could both be explained by partial melting in this experiment and could suggest that the Hugoniot of MgO preheated to 2300 K crosses its melting line just slightly above 240 GPa.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://iopscience.iop.org/1742-6596/500/6/062003/PublisherArticle
http://dx.doi.org/10.1088/1742-6596/500/6/062003DOIArticle
ORCID:
AuthorORCID
Asimow, P. D.0000-0001-6025-8925
Additional Information:© 2014 the authors. Content from this work may be used under the terms of the Creative Commons Attribution 3.0 licence. Any further distribution of this work must maintain attribution to the author(s) and the title of the work, journal citation and DOI. Published under licence by IOP Publishing Ltd. We are grateful to the late Prof. Thomas J. Ahrens for his deep interest and enthusiastic support of this research to the last days of his life. We thank M. Long, E. Gelle, and R. Oliver for technical help with our experiments. OVF thanks his newborn son Vladimir for the opportunity to finish writing and to submit this manuscript. Funded by NSF awards EAR-1119522 and EAR-1050269.
Funders:
Funding AgencyGrant Number
NSFEAR-1119522
NSFEAR-1050269
Issue or Number:6
Classification Code:PACS: 64.70.D-, 07.20.Ka, 62.50.-p
Record Number:CaltechAUTHORS:20140729-082224529
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20140729-082224529
Official Citation:MgO melting curve constraints from shock temperature and rarefaction overtake measurements in samples preheated to 2300 K O V Fat'yanov and P D Asimow 2014 J. Phys.: Conf. Ser. 500 062003
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:47545
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:29 Jul 2014 18:20
Last Modified:03 Oct 2019 06:54

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