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| Titel |
Electrical conductivity measurement of MgCO3 up to 6 GPa and 1000 K |
| VerfasserIn |
K. Mibe, S. Ono |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250065326
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| Zusammenfassung |
| Magnesite, MgCO3, is a naturally occurring carbonate mineral and is stable over a wide
range of pressure and temperature. It is known that magnesite is one of the important host
phases of carbon in the Earth’s deep interior. A knowledge of how magnesite’s electrical
properties vary as a function of pressure and temperature will be important in interpreting the
observed electrical conductivity map of the Earth’s interior. We, therefore, measured the
electrical conductivity of polycrystalline magnesite at pressures 3-6 GPa at high
temperatures using complex impedance spectroscopy in a multi-anvil high-pressure
apparatus. Synthetic powdered magnesite (MgCO3)(purity > 99.5%) was used as the
starting material. The measured electrical conductivity increased with increasing
pressure. The activation enthalpy calculated in the temperature range 650-1000 K also
increased with increasing pressure. The effect of pressure was interpreted as being the
activation volume in the Arrhenius equation, and the fitted data gave an activation
energy and volume of 1.76 ± 0.03 eV and -3.95 ± 0.78 cm3/mole, respectively. The
negative activation volume and relatively large activation energy observed in this
study suggests that the hopping of large polarons is the dominant mechanism for
the electrical conductivity over the pressure and temperature range investigated. |
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