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New Mixed Conductors Based on Doped Layered Perovskites

Published online by Cambridge University Press:  10 February 2011

Carlos Navas
Affiliation:
Dept. of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
Harry L. Tuller
Affiliation:
Dept. of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139
Hans-Conrad zur Loye
Affiliation:
Dept. of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208
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Abstract

A series of doped Ruddlesden-Popper phases, of general formula Sr3Ti2−xMxO7−δ (M=Al, Ga, Co), were synthesized and their electrical conductivity characterized as a function of temperature and oxygen partial pressure. For fixed-valent dopants, p-type conductivity predominates at p(O2)>10−5 atm, followed by a p(O2)-independent electrolytic regime, and n-type electronic conductivity at very low p(O2). The electrolytic regime exhibits activation energies in the range 1.7-1.8 eV. Doping with transition metals such as Co results in a very significant increase in total conductivity with a p-type conductivity at high p(O2). Furthermore, an apparent ionic regime at intermediate p(O2) is observed, characterized by high conductivity (>10−2 S/cm at 700 °C) and low activation energy (0.7 eV). This interpretation is consistent with iodometric measurements as interpreted by a defect chemical model. Other measurements are in progress to confirm this conclusion.

Type
Research Article
Copyright
Copyright © Materials Research Society 1999

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References

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