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Anisotropy of electrical conductivity in dry olivine
Author(s) -
Du Frane Wyatt L.,
Roberts Jeffery J.,
Toffelmier Daniel A.,
Tyburczy James A.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl023879
Subject(s) - anisotropy , olivine , electrical resistivity and conductivity , conductivity , isotropy , analytical chemistry (journal) , polaron , materials science , mineralogy , condensed matter physics , geology , physics , chemistry , electron , optics , chromatography , quantum mechanics
The electrical conductivity (σ) was measured for a single crystal of San Carlos olivine (Fo 89.1 ) for all three principal orientations over oxygen fugacities 10 −7 < < 10 1 Pa at 1100, 1200, and 1300°C. Fe‐doped Pt electrodes were used in conjunction with a conservative range of T, and time to reduce Fe loss resulting in data that is ∼0.15 log units higher in conductivity than previous studies. At 1200°C and = 10 −1 Pa, σ [100] = 10 −2.27 S/m, σ [010] = 10 −2.49 S/m, σ [001] = 10 −2.40 S/m. The dependences of σ on T and have been simultaneously modeled with undifferentiated mixed conduction of small polarons and Mg vacancies to obtain steady‐state activation energies: Ea [100] = 0.32 eV, Ea [010] = 0.56 eV, Ea [001] = 0.71 eV. A single crystal of dry olivine would provide a maximum of ∼10 0.4 S/m azimuthal σ contrast for T < 1500°C. The anisotropic results are combined to create an isotropic model with Ea = 0.53 eV.