Enhanced electronic conductivity by controlled self-doping in pyrochlores |
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Authors: | Xiao Haiyan Zhang Yanwen Weber William J |
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Institution: | Department of Materials Science & Engineering, University of Tennessee, Knoxville, TN 37996, USA. hxiao@utk.edu |
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Abstract: | Most 5d transition-metal (TM) pyrochlores exhibit metallic behavior, but 3d and 4d TM pyrochlores are generally electronic semiconductors or insulators. Here, we report a semiconductor-metal transition induced by introducing excess Ti metal as interstitials into Y(2)Ti(2)O(7). These Ti interstitials prefer anion vacant 8a sites or bridge sites between two neighboring cations along the <010> direction. Density functional theory calculations suggest that an increased electronic conductivity originates from the interplay between the extra Ti and its neighboring cations. These findings suggest a means for achieving metallic behavior in semiconducting pyrochlore oxides and tuning the electronic conduction in pyrochlores for their electrochemical applications in solid oxide fuel cells. |
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