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KMID : 1059519870310030215
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Journal of the Korean Chemical Society
1987 Volume.31 No. 3 p.215 ~ p.224
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Polaron Conductivity of Rutile Doped with MgO
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Kim Keu-Hong
Kim Hyung-Tack
Choi Jae-Shi
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Abstract
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The electrical conductivity measurements have been made on polycrystalline samples of various compositions in the MgO-TiO2 system from 600 to 1100℃ under PO2's of 10-8 to 10-1 atm. Plots of log σ vs. 1/T at constant PO2 are found to be linear with the inflections, and the activation energies are 1.94eV for the intrinsic range and 0.48eV for the extrinsic range, respectively. The log σ vs. log PO2 curves are found to be linear at constant temperature, and the conductivity dependences of PO2 are closely approximated by σ α PO2-1/6 for the extrinsic and σ α PO2-1/4 for the intrinsic range, respectively. The dominant defects in this system are believed to be oxygen vacancy for the extrinsic and Ti3+ interstitial for the intrinsic range. The conduction mechanisms in both the extrinsic and the intrinsic ranges are proposed by the results of the electrical conductivity dependence on the oxygen partial pressure. Polaron model was suggested in the extrinsic region by the conducativity dependences of temperature and PO2.
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KEYWORD
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