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Properties of LiF and Al_2O_3 to 240 GPa for Metal Shock Temperature Measurements

Holland, Kathleen G. and Ahrens, Thomas J. (1998) Properties of LiF and Al_2O_3 to 240 GPa for Metal Shock Temperature Measurements. In: Properties of Earth and Planetary Materials at High Pressure and Temperature. Geophysical Monograph Series. No.101. American Geophysical Union , pp. 335-343. ISBN 9780875900834. http://resolver.caltech.edu/CaltechAUTHORS:20141029-093003466

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Abstract

Shock temperature experiments employing a six-channel pyrometer were conducted on 200, 500, and 1000 A thick films of Fe sandwiched between 3-mm-thick anvils of Al203 and LiF to measure the thermal diffusivity ratios Al_20_3/Fe and LiF / Fe at high temperatures and pressures. Temperature decays of 3000 ± 800 K in 250 ns were observed at Fe pressures of 194 - 303 GPa, which reflect the conduction of heat from the thin metal films into the anvil material. These results were achieved via experiments employing LiF anvils at conditions of 164 - 165 GPa and 4190 - 4220 K and Al_2O_3 anvils at conditions of 156 - 304 GPa and 1290 - 2740 K. Thermal modeling of interface temperature versus time yields best fit thermal diffusivity ratios of 4 - 19 ± 1 (Fe/anvil) over the pressure and temperature range of the experiments. Calculated thermal conductivities for Fe, using electron gas theory, of 111 - 181 W /mK are used to calculate thermal conductivities for the anvil materials ranging from 2 to 13 W /mK. Debye theory predicts higher values of 8 to 35 W /mK. Data from previous experiments on thick (≥l00μm) films of Fe and stainless steel are combined with our present results from experiments on thin (≤1000 A) films to infer a 5860 ± 390 K Hugoniot temperature for the onset of melting of iron at 243 GPa. Our results address the question of whether radiation observed in shock temperature experiments on metals originates from the metal at the metal/anvil interface or from the shocked anvil. We conclude that the photon flux from the shocked assemblies recorded in all experiments originates from the metal. Within the uncertainties of the shock temperature data, the uncertainties in shock temperatures resulting from the radiation from the anvils is negligible. This is in direct disagreement with the conclusions of previous work by Kondo.


Item Type:Book Section
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http://dx.doi.org/10.1029/GM101p0335DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/GM101p0335/summaryPublisherArticle
Alternate Title:Properties of LiF and Al2O3 to 240 GPa for Metal Shock Temperature Measurements
Additional Information:© 1998 American Geophysical Union. Research supported by NSF grant EAR 92-19906 {Ahrens), EAR 95-06377 {Ahrens) and DMR 92-02587 {Atwater). We thank Neil Holmes and Michael Manga for their prompt and helpful reviews. We thank Harry Atwater and Irnran Hashim for use of the argon ion sputtering apparatus and for invaluable aid in making the iron coatings used for our 'thin film' experiments. We are grateful to Raymond Jeanloz and Michael Manga for technical discussions, to Stanley Love and Jessica Faust for helpful comments on the manuscript, as well as to M. Long, E. Gelle, A. Devora and Paul Carpenter for experimental assistance. Contribution No. 5847, Division of Geological and Planetary Sciences.
Funders:
Funding AgencyGrant Number
NSFEAR 92-19906
NSFEAR 95-06377
NSFDMR 92-02587
Subject Keywords:Mineralogy; Geophysics; Materials at high pressures; Materials at high temperatures
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Caltech Division of Geological and Planetary Sciences5847
Record Number:CaltechAUTHORS:20141029-093003466
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20141029-093003466
Official Citation:Holland, K. G. and Ahrens, T. J. (1998) Properties of LiF and Al2O3 to 240 GPa for Metal Shock Temperature Measurements, in Properties of Earth and Planetary Materials at High Pressure and Temperature (eds M. H. Manghnani and T. Yagi), American Geophysical Union, Washington, D. C.. doi: 10.1029/GM101p0335
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:50989
Collection:CaltechAUTHORS
Deposited By: Jason Perez
Deposited On:29 Oct 2014 19:34
Last Modified:29 Oct 2014 19:34

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