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Electrical conductivity of Ti-bearing hydrous olivine aggregates at high temperature and high pressure TEXT SIZE: A A A
We investigated the electrical conductivity of Ti-H-doped synthetic olivine aggregates at 4 GPa,873–1273 K, and controlled oxygen fugacities. Under a given pressure and temperature, electricalconductivity depends on both hydrogen and Ti content, but these samples show different conductivitybehavior from that observed in Tipoor sample such as San Carlos olivine. We found that when Ti content iscomparable to or larger than hydrogen content, Ti has notable effects on electrical conductivity, but theeffects of Ti is different between the Hrich and the Hpoor regimes. In the Hrich regime, electricalconductivity of olivine is weakly dependent on Ti content but has different sensitivity to water content than aTipoor olivine. In contrast, in the Hpoor regime, electrical conductivity of Tirich olivine issubstantially higher than the conductivity of Tipoor olivine. As a consequence, the effect of hydrogen for theTirich synthetic olivine on electrical conductivity is smaller than for the Tipoor (natural) olivine forthe modest H content expected in the asthenosphere, whereas in the Hpoor lithosphere Ti will enhance theelectrical conductivity substantially. Possible models to explain these observations are proposed includingthe interaction of Ti related defects and Hrelated defects as well as the charge transfer caused by thehopping conduction due to Ti3+? Ti4+under the Hpoor conditions. We conclude that the addition of Ti toolivine affects the behavior of Hrelated defects, and therefore the applications of results from Tiricholivine samples to the Tipoor real Earth need to be made with great care.
 

Publication name

 Journal of Geophysical Research: Solid Earth, 2020, 125(10), e2020JB020309

Author(s)

 Dai Lidong and Karato Shun-ichiro

Corresponding author(s) 

 DAI Lidong
 dailidong@vip.gyig.ac.cn
 1. Key Laboratory of High‐Temperature and High‐Pressure Study of the Earth's Interior, Institute of Geochemistry, Chinese Academy of Sciences, Guiyang, China
 2. Department of Earth and Planetary Sciences, Yale University, New Haven, CT, USA

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