Impedance spectroscopy of SnO2: CoO during sintering
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Cerri, J. A.
Leite, E. R.
Longo, Elson [UNESP]
Varela, José Arana [UNESP]
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SnO2:m mol% CoO (0.5 less than or equal to m less than or equal to 6.0) ceramic specimens were studied by impedance spectroscopy in the 5 Hz-13 MHz frequency range during heating cold-pressed specimens from room temperature to 1250 degrees C. The electrical resistivity during sintering decreases from 4 to 6 orders of magnitude in the 400-1500 K temperature range depending on the amount of CoO. An increase in electrical resistivity in the 570-670 K range is related to the release of adsorbed water. The results for the 970-1500 K show that the higher the amount of the CoO addition, the lower is the temperature at which SnO2:CoO reaches a minimum electrical resistivity. This suggests that oxygen point defects created by dissolution of cobalt ions in the SnO2 lattice are controlling the densification rate of these ceramics.
tin oxide, cobalt oxide dopant, resistivity, impedance spectroscopy, dilatometry, sintering aids
Materials Letters. Amsterdam: Elsevier B.V., v. 30, n. 1, p. 125-130, 1997.