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Shock compression of ilmenite

King, David A. and Ahrens, Thomas J. (1976) Shock compression of ilmenite. Journal of Geophysical Research, 81 (5). pp. 931-935. ISSN 0148-0227. https://resolver.caltech.edu/CaltechAUTHORS:20141106-144823605

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Abstract

Single- and reflected-shock compression measurements on single-crystal ilmenite (FeTiO_3) to pressures of 635 and 930 kbar, respectively, demonstrate anomalously large compressions above ∼320 kbar and imply the onset of one or more major phase changes at this pressure level which continue to occur to at least ∼600 kbar. The phase change onset pressure is considerably above the calculated upper bound of 193 kbar for the stability of ilmenite with respect to breakdown into wustite and rutile. Over the 300- to 600-kbar range, samples shocked along the c axis are consistently more compressible than those shocked along the perpendicular direction; at a given density the Hugoniot curves differ by 40 kbar. The observed density (6.25 g/cm^3) of the highest-pressure single-shock state implies that the shock-induced high-pressure phase has a zero-pressure density of at least 5.4 g/cm^3, or a density 13% greater than that of ilmenite. The reflected-shock data have a larger experimental uncertainty but indicate an even greater zero-pressure density for the high-pressure phase. The large density increase inferred restricts the possible nature of the high-pressure phase. These data are consistent with the 1300-kbar datum reported by Simakov et al. (1974) and with the disproportionment of ilmenite into mixed oxides in the rock salt (FeO) and fluorite (TiO_2) phases as observed (Liu, 1975) in static recovery experiments.


Item Type:Article
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http://dx.doi.org/10.1029/JB081i005p00931DOIArticle
http://onlinelibrary.wiley.com/doi/10.1029/JB081i005p00931/abstractPublisherArticle
Additional Information:Copyright 1976 by the American Geophysical Union. (Received November 18, 1974; revised August 26, 1975; accepted September 5, 1975.) This research was supported under contract NGL 05-002-105 and NSF grant GA 39042X. We appreciate the continued technical support of Harold Richeson and David Johnson. We thank Inge Bryhni, Curator of the Mineralogical-Geological Museum in Oslo, for the gift of the specimen material; A . A. Chodos for his microprobe analysis; and Rex V. Gibbons for assistance in examining our samples. We thank A. Reid, A. E. Ringwood, and L. Liu for sending us preprints of their papers. The comments of two anonymous reviewers were most helpful. Contribution 2552 of the Division of Geological and Planetary Sciences, California Institute of Technology.
Funders:
Funding AgencyGrant Number
NASANGL 05-002-105
NSFGA 39042X
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Caltech Division of Geological and Planetary Sciences2552
Issue or Number:5
Record Number:CaltechAUTHORS:20141106-144823605
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20141106-144823605
Official Citation:King, D. A., and T. J. Ahrens (1976), Shock compression of ilmenite, J. Geophys. Res., 81(5), 931–935, doi:10.1029/JB081i005p00931.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:51392
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:06 Nov 2014 23:17
Last Modified:03 Oct 2019 07:32

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