Electrochemical measurements on clay minerals for possible sensor applications |
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Authors: | E. E. Fokkens O. Schäf U. Guth |
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Affiliation: | (1) Sensor Research Center, D-17489 Greifswald, Germany;(2) Ernst-Moritz-Arndt University, D-17489 Greifswald, Germany |
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Abstract: | Natural clays were characterized by XRD, TGA and SEM/EDX, then pressed to pellets and analyzed by impedance measurements under various defined gas compositions and temperatures. From the Nyquist plot, conductivity values were calculated for the different clay samples. A strong dependence of the conductivity on the water vapour concentration at low temperatures was found for all investigated clay samples. Partial substitution of water by methanol led to a decrease in conductivity at low temperatures, confirming the essential role water plays in the conductivity mechanism at these temperatures. Increasing the temperature resulted in a decrease in conductivity, until a turn-over point was reached. Beyond this temperature an Arrhenius behaviour was observed, suggesting a change in the conductivity mechanism. Paper presented at the 5th Euroconference on Solid State Ionics, Benamádena, Spain, Sept. 13–20, 1998. |
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