Abstract: Electrical conductivity of talc was measured at 0.5 GPa and *473 to *1,300 K by using impedance spectroscopy both before and after dehydration. Before dehydration, the electrical conductivity of talc increased with temperature and is *10-4 S/m at 1,078 K. After dehydration, most of the talc changed to a mixture of enstatite and quartz and the total water content is reduced by a factor 6 or more. Despite this large reduction in the total water content, the electrical conductivity increased. The activation enthalpy of electrical conductivity (*125 kJ/mol) is too large for the conduction by free water but is consistent with conduction by small polaron. Our results show that a majority of hydrogen atoms in talc do not enhance electrical conductivity, implying the low mobility of the hydrogen atoms in talc. The observed small increase in conductivity after dehydration may be attributed to the increase in oxygen fugacity that enhances conductivity due to small polaron.
Citation: Duojun Wang , Shun-ichrio Karato. Electrical conductivity of talc aggregates at 0.5 GPa: inﬂuence of dehydration. Phys Chem Minerals (2013) 40:11–17, DOI 10.1007/s00269-012-0541-9