Materials sharing the hollandite structure were widely reported as fast ionic conductors. However, the ionic conductivity of KAlSi3O8 hollandite (K-hollandite), which can be formed during the subduction process, has not been investigated so far. Here first-principles calculations are used to investigate the potassium ion (K+) transport properties in K-hollandite. The calculated K+ migration barrier energy is 0.44 eV at a pressure of 10 GPa, an energy quite small to block the K+ migration in K-hollandite channels. The calculated ionic conductivity of K-hollandite is highly anisotropic and depends on its concentration of K+ vacancies. About 6% K+ vacancies in K-hollandite can lead to a higher conductivity compared to the conductivity of hydrated wadsleyite and ringwoodite in the mantle. K+ vacancies being commonly found in many K-hollandite samples with maximum vacancies over 30%, the formation of K-hollandite during subduction of continental or alkali-rich oceanic crust can contribute to the high conductivity anomalies observed in subduction zones. Publication name | GEOPHYSICAL RESEARCH LETTERS, 43 (12):6228-6233; 10.1002/2016GL069084 JUN 28 2016 | Author(s) | He, Yu; Sun, Yang; Lu, Xia; Gao, Jian; Li, Hong; Li, Heping | Corresponding author | LI Heping liheping@vip.gyig.ac.cn Chinese Acad Sci, Inst Geochem, Key Lab High Temp & High Pressure Study Earths In, Guiyang, Peoples R China. | View here for the details
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