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Materials (Basel). 2019 Jul 25;12(15). pii: E2359. doi: 10.3390/ma12152359.

Electronic Percolation Threshold of Self-Standing Ag-LaCoO3 Porous Electrodes for Practical Applications.

Author information

1
National Research and Development Institute for Cryogenics and Isotopic Technologies-ICIT Rm. Vâlcea, 4th Uzinei Str., P.O. Box 7 Râureni, 240050 Vâlcea, Romania. stanica.enache@icsi.ro.
2
National Research and Development Institute for Cryogenics and Isotopic Technologies-ICIT Rm. Vâlcea, 4th Uzinei Str., P.O. Box 7 Râureni, 240050 Vâlcea, Romania. mirela.dragan@icsi.ro.
3
National Research and Development Institute for Cryogenics and Isotopic Technologies-ICIT Rm. Vâlcea, 4th Uzinei Str., P.O. Box 7 Râureni, 240050 Vâlcea, Romania.
4
Acad. Evgeni Budevski Institute of Electrochemistry and Energy Systems, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.10, 1113 Sofia, Bulgaria.

Abstract

Perovskite LaCoO 3 materials have various applications, from selective permeable membranes and gas sensing devices to water splitting applications. However, the intrinsic electrical resistivity of the perovskite limits the applicative potential. To overcome that, Ag powder was used with LaCoO 3 to obtain porous composite electrodes with enhanced conductivities. For that, a series of composite Ag-LaCoO 3 powders were prepared into pellets and pre-sintered at various temperatures up to 1000 ∘ C. Their structural properties and morphology were investigated by X-ray diffraction and scanning electron microscopy. The electronic transport of compacted specimens was studied by impedance spectroscopy. The results indicate that the presence of Ag acts as pre-sintering additive to obtain porous electrodes, with porosity values as high as 40% at 50 vol. % Ag. Moreover, the overall electrical resistivity of the composite electrodes varied well over four orders of magnitude. The results are discussed within the generalized Bruggeman theory for effective media comprising arbitrarily shaped metallic and semiconducting inclusions.

KEYWORDS:

composite media; effective medium theory; electrical resistivity; perovskites; sintering

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