Transport properties of olivine grain boundaries from electrical conductivity experiments

Anne Pommier, David L. Kohlstedt, Lars N. Hansen, Stephen Mackwell, Miki Tasaka, Florian Heidelbach, Kurt Leinenweber

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Grain boundary processes contribute significantly to electronic and ionic transports in materials within Earth’s interior. We report a novel experimental study of grain boundary conductivity in highly strained olivine aggregates that demonstrates the importance of misorientation angle between adjacent grains on aggregate transport properties. We performed electrical conductivity measurements of melt-free polycrystalline olivine (Fo90) samples that had been previously deformed at 1200 °C and 0.3 GPa to shear strains up to γ = 7.3. The electrical conductivity and anisotropy were measured at 2.8 GPa over the temperature range 700–1400 °C. We observed that (1) the electrical conductivity of samples with a small grain size (3–6 µm) and strong crystallographic preferred orientation produced by dynamic recrystallization during large-strain shear deformation is a factor of 10 or more larger than that measured on coarse-grained samples, (2) the sample deformed to the highest strain is the most conductive even though it does not have the smallest grain size, and (3) conductivity is up to a factor of ~ 4 larger in the direction of shear than normal to the shear plane. Based on these results combined with electrical conductivity data for coarse-grained, polycrystalline olivine and for single crystals, we propose that the electrical conductivity of our fine-grained samples is dominated by grain boundary paths. In addition, the electrical anisotropy results from preferential alignment of higher-conductivity grain boundaries associated with the development of a strong crystallographic preferred orientation of the grains.

Original languageEnglish (US)
Article number41
JournalContributions to Mineralogy and Petrology
Volume173
Issue number5
DOIs
StatePublished - May 1 2018

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grain boundary
olivine
Transport properties
electrical conductivity
Grain boundaries
grain boundaries
transport properties
electrical resistivity
conductivity
shear strain
preferred orientation
experiment
Experiments
Anisotropy
anisotropy
grain size
shear
Dynamic recrystallization
Shear strain
misalignment

Keywords

  • Electrical anisotropy
  • Electrical conductivity
  • Grain boundaries
  • Olivine
  • Shear strain

ASJC Scopus subject areas

  • Geophysics
  • Geochemistry and Petrology

Cite this

Transport properties of olivine grain boundaries from electrical conductivity experiments. / Pommier, Anne; Kohlstedt, David L.; Hansen, Lars N.; Mackwell, Stephen; Tasaka, Miki; Heidelbach, Florian; Leinenweber, Kurt.

In: Contributions to Mineralogy and Petrology, Vol. 173, No. 5, 41, 01.05.2018.

Research output: Contribution to journalArticle

Pommier, Anne ; Kohlstedt, David L. ; Hansen, Lars N. ; Mackwell, Stephen ; Tasaka, Miki ; Heidelbach, Florian ; Leinenweber, Kurt. / Transport properties of olivine grain boundaries from electrical conductivity experiments. In: Contributions to Mineralogy and Petrology. 2018 ; Vol. 173, No. 5.
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