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A Fluorite Isotype of SnO_2 and a New Modification of TiO_2: Implications for the Earth's Lower Mantle

Liu, Lin-Gun (1978) A Fluorite Isotype of SnO_2 and a New Modification of TiO_2: Implications for the Earth's Lower Mantle. Science, 199 (4327). pp. 422-425. ISSN 0036-8075. https://resolver.caltech.edu/CaltechAUTHORS:20150209-152115465

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Abstract

The existence of a cubic fluorite-type SnO_2 and a hexagonal TiO_2 (which may be related to the fluorite structure) have been demonstrated by an in situ x-ray diffraction study in which a diamond-anvil pressure cell was used after the samples had been heated by a continuous yttrium-aluminum-garnet laser. At room temperature, the lattice parameter for SnO_2 (fluorite) is a = 4.925 ± 0.005 angstroms and those for Ti_2 (fluorite-related) are a = 9.22 ± 0.01 angstroms and c = 5.685 ± 0.006 angstroms at about 250 kilobars. The volume change associated with the transition from rutile to fluorite (or related structure) is about –8 percent for SnO_2 and –10.5 percent for TiO_2 at transition. Upon release of pressure, both the fluorite-type SnO_2 and the TiO_2 reverted to the α-PbO_2 structure at room temperature. The hypothesis that the earth's lower mantle is composed of oxide phases might be feasible if it were possible for SiO_2 to possess the fluorite structure or its related forms at high pressure, as shown for SnO_2 and TiO_2 in this study. The oxide hypothesis proposed here differs from that postulated by Birch in that the primary coordination of silicon is 6 for Birch's hypothesis and 8 for the hypothesis presented here.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1126/science.199.4327.422DOIArticle
http://www.sciencemag.org/content/199/4327/422PublisherArticle
http://www.jstor.org/stable/1745802JSTORArticle
Alternate Title:A Fluorite Isotype of SnO2 and a New Modification of TiO2: Implications for the Earth's Lower Mantle
Additional Information:© 1978 American Association for the Advancement of Science. 18 July 1977; Revised 12 September 1977. I thank J. R. Cleary for commenting on the manuscript. This research was supported by the California Institute of Technology's President Venture Fund. Contribution No. 2941, Division of Geological and Planetary Sciences, California Institute of Technology.
Funders:
Funding AgencyGrant Number
Caltech President’s FundUNSPECIFIED
Other Numbering System:
Other Numbering System NameOther Numbering System ID
Caltech Division of Geological and Planetary Sciences2941
Issue or Number:4327
Record Number:CaltechAUTHORS:20150209-152115465
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150209-152115465
Official Citation:LIU, L.-G. (1978). A Fluorite Isotype of SnO2 and a New Modification of TiO2: Implications for the Earth's Lower Mantle. Science, 199(4327), 422-425. doi: 10.1126/science.199.4327.422
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:54582
Collection:CaltechAUTHORS
Deposited By: Joanne McCole
Deposited On:10 Feb 2015 05:19
Last Modified:03 Oct 2019 07:59

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