Oxygen vacancy diffusion in davemaoite (CaSiO₃ perovskite) : Implications for the redox equilibrium and the electrical conductivity of Earth's lower mantle

DOI zum Zitieren der Version auf EPub Bayreuth: https://doi.org/10.15495/EPub_UBT_00009422
URN to cite this document: urn:nbn:de:bvb:703-epub-9422-9

Title data

Schulze, Maximilian ; Steinle-Neumann, Gerd:
Oxygen vacancy diffusion in davemaoite (CaSiO₃ perovskite) : Implications for the redox equilibrium and the electrical conductivity of Earth's lower mantle.
In: Earth and Planetary Science Letters. Vol. 679 (2026) . - 119861.
ISSN 0012-821X
DOI der Verlagsversion: https://doi.org/10.1016/j.epsl.2026.119861

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Project information

Project title:	Project's official title Project's id Die Rolle leichter Elemente an der Kern-Mantel Grenze - Partitionierung, Entmischung und Transport 521548786 Open Access Publizieren No information
Project financing:	Deutsche Forschungsgemeinschaft

Abstract

Davemaoite (CaSiO3), a major rock-forming mineral in the Earth’s lower mantle, adopts a perovskite structure, which is known for the rapid diffusion of extrinsic oxygen vacancies (OV). Here, we use molecular dynamics simulations in conjunction with a machine learning potential to systematically investigate extrinsic OV diffusion in davemaoite at lower mantle conditions. We determine diffusion coefficients (Dv) for a series of temperatures along isobars of 25, 50, 75, 100 and 125 GPa and find that computed diffusivities closely follow an Arrhenian behavior. The pre-exponential factor is pressure independent with logDv∘=-6.53 ± 0.06 and the activation enthalpy increases nonlinearly with pressure from 0.87 eV to 1.66 eV. On the basis of the Arrhenian model, we predict that Dv decreases throughout the lower mantle by at least one order of magnitude along geotherms representative of the ambient mantle and subducted lithosphere. We argue that despite the high OV diffusivities, the davemaoite component of subducted oceanic crust does not achieve complete redox equilibration with the surrounding mantle on its way to the core-mantle boundary, and that significant redox exchange is limited to the upper parts of the lower mantle. Finally, we provide arguments that the electrical conductivity of most parts of the lower mantle cannot be explained by ionic conductivity and that its electrical conductivity must therefore be determined by iron-induced polaron hopping.

Further data

Item Type:	Article in a journal
Keywords:	Perovskite; Oxygen vacancy diffusion; Lower mantle; Redox equilibrium; Ionic conductivity; Arrhenius relation; Machine learning potential molecular dynamics
DDC Subjects:	500 Science > 550 Earth sciences, geology
Institutions of the University:	Research Institutions > Central research institutes > Bavarian Research Institute of Experimental Geochemistry and Geophysics - BGI Research Institutions Research Institutions > Central research institutes
Language:	English
Originates at UBT:	Yes
URN:	urn:nbn:de:bvb:703-epub-9422-9
Date Deposited:	16 Jun 2026 07:33
Last Modified:	16 Jun 2026 07:34
URI:	https://epub.uni-bayreuth.de/id/eprint/9422

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