Paradox of Peroxy Defects and Positive Holes in Rocks - Part I: Effect of Temperature
| Autor: | Friedemann Freund, Minoru M. Freund |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2015 |
| Předmět: |
Thermodynamic equilibrium
Peroxy defects FOS: Physical sciences Positive hole charge carriers Thermal activation Electric charge law.invention Physics - Geophysics law Electrical resistivity and conductivity Vacancy defect Electrical conductivity High-grade metamorphic rocks Crystallization Dissolution Magnesium oxide Earth-Surface Processes Geology Geophysics (physics.geo-ph) Condensed Matter - Other Condensed Matter Chemical physics Igneous rocks Charge carrier Other Condensed Matter (cond-mat.other) Solid solution |
| Popis: | Though ubiquitous in minerals of igneous and high-grade metamorphic rocks, peroxy defects have been widely overlooked in the past. The charge carriers of interest are positive holes, chemically equivalent to O$^-$ in a matrix of O$^{2-}$, physically defect electrons in the O$^{2-}$ sublattice, highly mobile, able to propagate fast and far. O$^-$ are oxidized relative to O$^{2-}$. As such O$^-$ are not supposed to exist in minerals and rocks that come from deep within the Earth crust or upper mantle, where the environments are overwhelmingly reduced. In order to understand how peroxy defects are introduced, we look at peroxy defects in a crystallographically and compositionally well characterized model system: single crystals of nominally high-purity MgO, grown from the melt under highly reducing conditions. During crystallization the MgO crystals incorporate OH$^-$ through dissolution of traces of H$_2$O into the MgO matrix, leading to a solid solution (ss) Mg$_{1-\delta}$(OH)$_{2\delta}$O$_{1-2\delta}$, where $\delta$ Comment: 30 pages, 8 figures |
| Databáze: | OpenAIRE |
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