Ceramics-Silikáty 36, (2) 69 - 72 (1992) |
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THE TEMPERATURE DEPENDENCE OF TBE ELECTRIC CONDUCTIVITY OF UNFIRED PORCELAIN MIXTURE
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Kozík Tomáš 1, Trnovcová Viera 2, Mariani Emil 2,
Štubňa Igor 1,
Roháč Ján 1
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1 Faculty of Pedagogy, 949 14 Nitra, Czechoslovakia
2 Institute of Physics, Slovak Academy of Sciences, 842 28 Bratislava, Czechoslovakia
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Polar water molecules and dissociated H⁺ , OH⁻ ions which are bonded to the surfaces of kaolinite crystals represent the physically bonded water (PBW). The removal of PBW is completed at 360 ± 10°C. Above this temperature ac and de conductivities are mainly dependent on the motion of alkaline ions Na⁺ , K⁺ , Ca⁺⁺ until the constitution water begins to be removed (440-460°C). After thermal treatment at 550°C, the changes of conductivity in low temperature region were detected. It was caused by the water and OH⁻ ions which were released in the dehydroxylation and bonded on surface defects and free alkaline ions. |
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