Electrical conductivity measurements on synthetic olivines and on olivine, enstatite and diopside from Dreiser Weiher, Eifel (Germany) under defined thermodynamic activities as a function of temperature and pressure

Hinze, Ε.; Will, G.; Cemič, Ladislav

doi:10.1016/0031-9201(81)90068-6

Cited by 45 publications

(34 citation statements)

References 20 publications

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“…The reduction of activation enthalpy and enhancement of electrical conductivity with Huebner and Voigt (1988); C2006, modeled data of dry olivine by Constable (2006) under quartz-fayalite-magnetite (QFM) buffer at ambient pressure; XSD2000, measured data of dry San Carlos olivine at 4 GPa under Mo-MoO 2 buffer by Xu et al (2000); YKMN2011, measured data of dry plagioclase by Yang et al (2011a, b). The slight deviation of some data-points at *1,000°C was probably caused by the relatively higher background conductance at this temperature increasing Fe content has also been observed for olivine, garnet and ringwoodite (Hinze et al 1981;Romano et al 2006;). The electrical conductivity of the dry augite is *1-3 orders of magnitude higher than that of dry olivine depending on temperature (Fig.…”

Section: Conduction Mechanismsmentioning

confidence: 78%

“…Results from laboratory studies of the electrical conductivity of Earth materials (e.g., minerals/rocks) are important in the interpretation of conductivity profiles versus depth derived from field observations and of conductivity anomalies inside the Earth. The electrical properties of Earth materials are strongly dependent on factors such as chemical composition, temperature, oxygen fugacity and crystallographic orientation and slightly on pressure, and the influence of these parameters has been investigated and discussed in some previous publications (Shankland 1975;Hinze et al 1981; Roberts and Tyburczy 1991;Huebner and Dillenburg 1995;Xu et al 2000;Du Frane et al 2005;Romano et al 2006;Tyburczy 2007;. The grain size of minerals in the Earth's interior varies from *10 lm (e.g., some ultra-mylonites in strong shear zones) to several mm or even larger depending on the thermal and mechanical history (see Chapter 13 in Karato 2008; and references therein).…”

Section: Introductionmentioning

confidence: 99%

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Grain size effect on the electrical conductivity of clinopyroxene

Yang

Heidelbach

2011

Contrib Mineral Petrol

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Complex impedance spectra of polycrystalline samples (with grain size fractions *5-63, 63-160 and 160-250 lm) and a single crystal sample (with orientation parallel to b), prepared from a natural megacryst augite, were measured in a piston cylinder apparatus at 10 kbar and 500-1,000°C and with a Solartron 1260 Impedance/ Gain Phase analyzer over a frequency range of 0.1-10 6 Hz. The main charge carriers are attributed to small polarons, and the activation enthalpy is 83 ± 3 to 90 ± 3 kJ/mol. The measured electrical conductivity shows no difference between the polycrystalline and single crystal samples, suggesting independence of electrical conductivity on grain size given a change above *5 lm. The electrical conductivity of augite is much higher than that of olivine, indicating that, if regionally enriched, augites may lead to zones of high electrical conductivity and electrical anisotropy in the deep lithosphere.

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Section: Conduction Mechanismsmentioning

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Grain size effect on the electrical conductivity of clinopyroxene

Yang

Heidelbach

2011

Contrib Mineral Petrol

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“…Fayalite is electrically conductive, 33 and increasing fayalite concentrations exsolved from ZVI phases has been shown to increase electrical conductivity of the composite. 34 Thus, fayalite may have facilitated corrosion of ZVI in the corn stover and switchgrass biochars by enhancing electron transport during oxidation and also increasing defect site population in the ZVI continuum. Oxidation of both fayalite and ZVI is observed as transformation to quartz and hematite as revealed by XRD patterns of 900°C HTT BC-ZVI produced from corn stover and switchgrass ( Figures S2, S4).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Sustainable Pyrolytic Production of Zerovalent Iron

Lawrinenko

Laird

Leeuwen

2016

ACS Sustainable Chem. Eng.

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Pyrolysis of biorenewable feedstocks and iron oxides is potentially a greener and more sustainable pathway to producing zerovalent iron (ZVI) for environmental rehabilitation. The resulting biochar-zerovalent iron (BC-ZVI) also shows improved remediation kinetics of trichloroethylene over conventional ZVI. Understanding the transformations of iron to ZVI and the influence of feedstock chemistry on ZVI is critical to the production of BC-ZVI and has not been reported previously. BC-ZVI production was studied by one-step pyrolysis of cellulose, corn stover, dried distillers' grain, red oak, and switchgrass pretreated with FeCl 3 . Pyrolysis at 900 °C effectively reduced Fe to ZVI with most feedstocks; however, the association of silicon (Si) and phosphorus (P) with Fe resulted in formation of fayalite and Fe phosphates and phosphides, which limited ZVI production efficiency and/or facilitated corrosion of ZVI. Dispersion of ZVI phases on biochar surfaces and association with Si facilitated oxidation of ZVI due to greater accessibility to oxygen and enhanced corrodibility of ZVI in association with fayalite. Feedstocks low in Si and P such as cellulose and red oak yield BC-ZVI suitable for environmental applications.

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“…Many research papers and review papers have been published giving a thorough overview of the physical and chemical parameters that control the electrical charge transport in rocks and minerals (Olhoeft, 1976;Olhoeft, 1979;Cemic et al, 1980Cemic et al, , 1981Duba et al, 1974Glover and Vine, 1995;Glover et al 1996;Hinze et al, 1981Hinze et al, , 1982Revil et al, 1996;Ruffet et al, 1991Ruffet et al, , 1995. Within the last 10 years many efforts were concentrated on the application of more sophisticated techniques to get a deeper insight into the physical and chemical parameters that control the electrical charge transport.…”

Section: Introductionmentioning

confidence: 98%

Electrical Properties of Crustal and Mantle Rocks – A Review of Laboratory Measurements and their Explanation

Nover¹

2005

Surv Geophys

112

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The electrical properties of rocks and minerals are controlled by thermodynamic parameters like pressure and temperature and by the chemistry of the medium in which the charge carriers move. Four different charge transport processes can be distinguished. Electrolytic conduction in fluid saturated porous rocks depends on petrophysical properties, such as porosity, permeability and connectivity of the pore system, and on chemical parameters of the pore fluid like ion species, its concentration in the pore fluid and temperature. Additionally, electrochemical interactions between water dipoles or ions and the negatively charged mineral surface must be considered. In special geological settings electronic conduction can increase rock conductivities by several orders of magnitude if the highly conducting phases (graphite or ores) form an interconnected network. Electronic and electrolytic conduction depend moderately on pressure and temperature changes, while semiconduction in mineral phases forming the Earth's mantle strongly depends on temperature and responds less significantly to pressure changes. Olivine exhibits thermally induced semiconduction under upper mantle conditions; if pressure and temperature exceed $ 14 GPa and 1400°C, the phase transition olivine into spinel will further enhance the conductivity due to structural changes from orthorhombic into cubic symmetry. The thermodynamic parameters (temperature, pressure) and oxygen fugacity control the formation, number and mobility of charge carriers. The conductivity temperature relation follows an Arrhenius behaviour, while oxygen fugacity controls the oxidation state of iron and thus the number of electrons acting as additional charge carriers. In volcanic areas rock conductivities may be enhanced by the formation of partial melts under the restriction that the molten phase is interconnected. These four charge transport mechanisms must be considered for the interpretation of geophysical field and borehole data. Laboratory data provide a reproducible and reliable database of electrical properties of homogenous mineral phases and heterogenous rock samples. The outcome of geoelectric models can thus be enhanced significantly. This review focuses on a compilation of fairly new advances in experimental laboratory work together with their explanation.

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Electrical conductivity measurements on synthetic olivines and on olivine, enstatite and diopside from Dreiser Weiher, Eifel (Germany) under defined thermodynamic activities as a function of temperature and pressure

Cited by 45 publications

References 20 publications

Grain size effect on the electrical conductivity of clinopyroxene

Grain size effect on the electrical conductivity of clinopyroxene

Sustainable Pyrolytic Production of Zerovalent Iron

Electrical Properties of Crustal and Mantle Rocks – A Review of Laboratory Measurements and their Explanation

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