In order to check the consistency of the well known Heywang model for explaining the PTC effect, DC resistivity, AC impedance and thermoelectric power measurements have been performed on Nb-doped BaTiO3 ceramics. It is found that the Heywang model can fit the shape of the experimental DC resistivity data, but it appears that the donor density in the grain is much lower than the nominal one, while impedance measurements emphasize the role of the grain boundary resistance. The thermoelectric power exhibits an anomalous behavior in contradiction with the usual semiconductivity mechanism of electrical transport.
机构:Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia
Kowalski, K
Ijjaali, M
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机构:Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia
Ijjaali, M
Bak, T
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机构:Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia
Bak, T
Dupre, B
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机构:Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia
Dupre, B
Nowotny, J
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Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, AustraliaUniv New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia
Nowotny, J
Rekas, M
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机构:Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia
Rekas, M
Sorrell, CC
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机构:Univ New S Wales, Sch Mat Sci & Engn, Ctr Mat Res Energy, Sydney, NSW 2052, Australia