Nonstoichiometry and Mixed Conduction in α-Ta2O5 |
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| Authors: | Gyeong M. Choi&# ,Harry L. Tuller&# |
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| Affiliation: | Crystal Physics and Optical Electronics Laboratory, Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 |
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| Abstract: | Electrical conductivity of single-crystal and polycrystalline Ta2O5 was measured as a function of composition, temperature, and oxygen partial pressure ( P O2) by both dc and ac complex impedance methods. A defect model based on the assumption of predominant disorder on the oxygen sublattice is proposed to explain the observed nonstoichiometry of α-Ta2O5. The defect model is consistent with the observed P O2-independent ionic conductivity and the P −1/4O2-dependent electronic conductivity. Blocking of the ionic component was observed at low P O2. Both the electronic and ionic components of conductivity were found to decrease with time. This aging phenomena is related to destabilization of the a phase. |
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| Keywords: | tantalum ionic conductors electronic conduction oxygen partial pressure models |
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