Frequency dependent electrical properties of dunite as functions of temperature and oxygen fugacity

Roberts, Jeffery J.; Tyburczy, J. A.

doi:10.1007/bf00203054

Cited by 37 publications

(26 citation statements)

References 43 publications

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“…However, laboratory data of the electrical properties of olivine is needed to constrain the modeled inversion of MT data from the field. This study improves upon previous studies done on the electrical conductivity of natural olivine (Duba 1972;Roberts and Tyburczy 1993a;Constable and Duba 2002) by complementing other studies Dai et al 2008b) on electrical impedance experiments on iron-bearing, synthetic Fo 90 under various temperature, grain size and oxygen fugacity conditions. Using synthetic sol-gel olivine, we attempt to avoid possible issues that can be encountered when measuring the electrical conductivity in the laboratory on natural material by acknowledging that synthetic olivine is free from impurity atoms, is fully buffered by enstatite and has a very low water concentration.…”

Section: Introductionsupporting

confidence: 78%

“…graingrain boundary and electrode-grain interfaces), are likely to produce distinct arc signatures as long as their RC values are substantially different. Figure 4b shows that conductivity in a single crystal along a particular crystallographic axis is higher than for aggregates (Constable and Duba 1990;Roberts and Tyburczy 1993a), illustrating the blocking nature of the grain boundaries present in the aggregate at lower fO 2 . Also it appears that the difference between the Red Sea olivine (single crystal) (Schock et al 1989) and San Carlos olivine (single crystal) (Du Frane et al 2005) is almost one order of magnitude, thus highlighting the natural compositional variation and possibly more oxidized state of San Carlos material.…”

Section: Results Of Circuit Modelingmentioning

confidence: 96%

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Electrical conductivity of synthetic iron-bearing olivine

2009

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The electrical conduction in synthetic, dry polycrystalline, iron-bearing olivine (Fo 90 ) was investigated as a first-order approach to the electrical conductivity in the upper mantle. This fundamental study is of great importance to better understand the charge-transport mechanisms seen in olivine. Conduction processes in synthetic samples are not influenced by a complex geological history in contrast to conductivity in natural olivine. The experiments show that the apparent activation energy for conductivity for Fo 90 is 230 kJ mol -1 . In currently accepted defect modeling, natural and synthetic olivine requires a mechanism involving small polaron formation (Fe Á Mg and magnesium vacancies (V Mg ) as the dominant diffusing species to explain a fO 2 1/6 relation to electrical conduction. Here, Fo 90 shows no contribution of small polarons to conductivity at temperatures between 1,000 and 1,200°C and almost no dependence on fO 2 . Instead, under reducing conditions magnesium vacancies (and electrons) appear to be the major charge carriers.

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Section: Introductionsupporting

confidence: 78%

Section: Results Of Circuit Modelingmentioning

confidence: 96%

Electrical conductivity of synthetic iron-bearing olivine

2009

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“…Grain boundary, a general property of rocks, is therefore receiving increasing attention from researchers. Peridotite is the most important rock in the upper mantle, and the influence of grain boundary on its electrical conductivity has been studied in detail (Tyburczy and Roberts, 1990;Roberts and Tyburczy, 1991, 1993, 1994Xu et al, 1998Xu et al, , 2000ten Grotenhuis et al, 2004;Watson et al, 2010;Wu et al, 2010). However, the relation between the total conductivity, grain boundary and grain interior conductivity for andesite remains unclear till now.…”

Section: Introductionmentioning

confidence: 99%

Experimental study on the electrical conductivity of quartz andesite at high temperature and high pressure: evidence of grain boundary transport

Hui

Zhang

et al. 2015

Solid Earth

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Abstract. In this study, the electrical conductivity of quartz andesite was measured in situ under conditions of 0.5-2.0 GPa and 723-973 K using a YJ-3000t multi-anvil press and a Solartron-1260 Impedance/Gain-Phase Analyzer. Experimental results indicate that grain interior transport controls the higher frequencies (10 2 -10 6 Hz), whereas the grain boundary process dominates the lower frequencies (10 −1 -10 2 Hz). For a given pressure and temperature range, the relationship between Log σ and T −1 follows the Arrhenius relation. As temperature increased, both the grain boundary and grain interior conductivities of quartz andesite increased; however, with increasing pressure, both the grain boundary and grain interior conductivities of the sample decreased. By the virtue of the dependence of grain boundary conductivity on pressure, the activation enthalpy and the activation volume were calculated to be 0.87-0.92 eV and 0.56 ± 0.52 cm 3 mol −1 , respectively. The small polaron conduction mechanism for grain interior process and the ion conduction mechanism for grain boundary process are also discussed.

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“…In material science, for example, the IS method is used to characterize the electrical properties of materials and separate the bulk, grain boundary, and electrode processes of polycrystalline materials. [1][2][3][4][5][6][7][8] The IS method is also available for in situ analysis of materials under extreme conditions and can reveal many important properties such as conductivity, interface density, as well as dielectric characteristics. [9][10][11][12] Actually, the IS method has been introduced in mineral electrical property research under high pressure.…”

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confidence: 99%