Impedance spectroscopy of upper mantle Earth materials

James Tyburczy, J. J. Roberts

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Earth scientists study electrical properties of Earth materials to understand mechanisms of transport and deformation under conditions existing in the Earth's interior, and for comparison with direct determinations of the conductivity - depth structure of the Earth. We have performed impedance spectroscopic studies of natural and artificial (hot-pressed and sintered) rocks composed of (Mg .9Fe .1) 2SiO 4 olivine, a major constituent of the Earth's upper mantle between 40 and 400 km depth. The studies were performed over the frequency range 10 5 to 10 -4 Hz at 1 bar total pressure and temperatures of 800 - 1400 °C under controlled oxygen atmospheres. Complex impedance plane analysis of the results shows depressed impedance arcs corresponding to grain interior and grain boundary transport in series, analogous to the behavior of zirconia and other materials. Distinct grain boundary phases that might cause the resistive grain boundary behavior are not observed. The exponent of the oxygen pressure dependence of the grain boundary conductivity ranges from 0.02 to -0.08, which is very different than the 1/5.5 to 1/7 dependence of the polaronic grain interior mechanism. However, lack of constraints on the composition of the intergranular material limit interpretation of these exponents in terms of mechanism. Key issues for application to the Earth's interior are determination of the mechanism and pressure dependence of the grain boundary transport.

Original languageEnglish (US)
Title of host publicationMaterials Research Society Symposium - Proceedings
PublisherMaterials Research Society
Pages283-288
Number of pages6
Volume411
StatePublished - 1996
EventProceedings of the 1995 MRS Fall Meeting - Boston, MA, USA
Duration: Nov 26 1995Dec 1 1995

Other

OtherProceedings of the 1995 MRS Fall Meeting
CityBoston, MA, USA
Period11/26/9512/1/95

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials

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