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Ábrám, Emese; Sinclair, Derek C.; West, Anthony R.

doi:10.1023/a:1014435112280

Cited by 31 publications

(8 citation statements)

References 4 publications

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“…It is obvious from the figure that impedance of the samples decreases with an increase in temperature, and this can be attributed to the fact that the conduction process is thermally activated. One semicircle was observed in the measured temperature range followed by a low-frequency inclined spike due to either the diffusion of ions in the electrode or electrode polarization . Such a spike is characteristic of a blocking double-layer capacitance produced by the blocking of ionic charge carriers at the electrode sample interface.…”

Section: Resultsmentioning

confidence: 93%

“…One semicircle was observed in the measured temperature range followed by a low-frequency inclined spike due to either the diffusion of ions in the electrode or electrode polarization. 33 Such a spike is characteristic of a blocking double-layer capacitance produced by the blocking of ionic charge carriers at the electrode sample interface. This also proves that charge carriers are oxide ions rather than electrons.…”

Section: Transmission Electron Microscopy (Tem)mentioning

confidence: 99%

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Role of Bond Strength on the Lattice Thermal Expansion and Oxide Ion Conductivity in Quaternary Pyrochlore Solid Solutions

et al. 2012

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Quaternary pyrochlore-type solid solutions, CaGdZrNb(1-x)Ta(x)O(7) (x = 0, 0.2, 0.4, 0.6, 0.8, 1), were prepared by a high-temperature ceramic route. The pyrochlore phases of the compounds were confirmed by powder X-ray diffraction (XRD), Raman spectroscopy, and transmission electron microscopy. The crystallographic parameters of the pyrochlore compounds were accurately determined by Rietveld analysis of the powder XRD data. The isovalent substitution of Ta in place of Nb at the B site can reveal the effect of chemical bonding on lattice thermal expansion and oxide ion conductivity because both Nb and Ta have the same ionic radius (0.64 Å). Lattice thermal expansion coefficients of the samples were calculated from high-temperature XRD measurements, and it was found that the thermal expansion coefficient decreases with substitution of Ta. Oxide ion conductivity measured by a two-probe method also shows the same trend with substitution of Ta, and this can be attributed to the high bond strength of the Ta-O bond compared to that of the Nb-O bond. Microstructural characterization using scanning electron microscopy proves that the size of the grains has a small effect on the oxide ion conductivity. Our studies established the role of chemical bonding in deciding the conductivity of pyrochlore oxides and confirmed that the 48f-48f mechanism of oxide ion conduction is dominant in pyrochlore oxides.

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Section: Resultsmentioning

confidence: 93%

Section: Transmission Electron Microscopy (Tem)mentioning

confidence: 99%

Role of Bond Strength on the Lattice Thermal Expansion and Oxide Ion Conductivity in Quaternary Pyrochlore Solid Solutions

et al. 2012

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“…41 Quantities h c and σ eff A in Equation 2 were determined by fitting (York's method) the resistance as function of height for both thick-and thin-cathode sample data at several pressures. 42 The quality of the fits resulted in a mean R 2 value of 0.98, with the lowest single value being 0.92.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Carbon Additives on the Microstructure and Conductivity of Alkaline Battery Cathodes

Nevers

Peterson

Robertson

et al. 2014

J. Electrochem. Soc.

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This paper describes research to understand the relationships between materials, microstructure, and performance for primary alkaline battery cathodes composed primarily of electrolytic manganese dioxide (EMD). Specifically, the effect of various carbon additives on electronic transport within cathodes was investigated. Of the various carbon additives investigated, TIMCAL BNB90 was the best performer and graphene nanopowder was the next best. These additives had the lowest Scott density and highest BET surface area of the tested additives, and exhibited well-connected and elongated carbon pathways in SEM/FIB cross sections. Additionally, this work shows a decrease in electronic conductivity for the porous cathode in the presence of KOH electrolyte. The two top-performing cathodes, when wet with concentrated KOH had a conductivity that was about 30% below that of the dry conductivity.

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“…5, the fitted curves are in accordance with measured data. According to the fitted results, the electrical capacity is 5.85 9 10 -10 F. As Abram et al reported that the capacitances for the bulk and grain-boundary components are of the order of 10 -12 F and 10 -11 -10 -8 F [26,27], respectively, it indicates that the impedance arc should mainly reflect the grain-boundary effect in each impedance spectrum. It means that the resistivities of the SSZ ceramics resulted mostly from the grain-boundary effect which is governed by the Schottky thermoelectric effect, and the grain effect resistivity is negligible, these are in agreement with the report by Bueno et al [28].…”

Section: Impedance Analysismentioning

confidence: 85%

Zr-substituted SnO2-based NTC thermistors with wide application temperature range and high property stability

Ouyang

Zhang

2015

J Mater Sci: Mater Electron

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Zr-substituted SnO 2 -based ceramics (Sn 0.95-x Sb 0.05 Zr x O 2 , x B 0.1) were prepared by using a wet-chemical synthesis method. The results show that the prepared ceramics have a pure tetragonal phase as that of SnO 2 and have a typical characteristic of negative temperature coefficient (NTC) of resistivity over a wide temperature range from -50 to 300°C. The room-temperature resistivity q 25 and material constant B 25/85 of the NTC thermistors increase from 4.77 X cm to 4.89 9 10 7 X cm and from 641 to 5085 K, respectively, when the content of Zr, x, changes from 0 to 0.1. The NTC thermistors also show high cyclic stability and ageing resistance. The analysis of impedance spectra reveals that the NTC effect mainly resulted from the grain-boundary contribution, and the conduction mechanisms of the Sn 0.95-x Sb 0.05 Zr x O 2 thermistors combine with the electron-hopping conduction and band conduction.

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Untitled

Cited by 31 publications

References 4 publications

Role of Bond Strength on the Lattice Thermal Expansion and Oxide Ion Conductivity in Quaternary Pyrochlore Solid Solutions

Role of Bond Strength on the Lattice Thermal Expansion and Oxide Ion Conductivity in Quaternary Pyrochlore Solid Solutions

The Effect of Carbon Additives on the Microstructure and Conductivity of Alkaline Battery Cathodes

Zr-substituted SnO2-based NTC thermistors with wide application temperature range and high property stability

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