DC Conductivity of Illite with Fly-Ash between 20 – 1050 °C

Abstract

The temperature dependence of the electrical DC conductivity of fly-ash and illite-based ceramics was measured in the temperature range of 20 – 1050 °C. The measurements were done for illite samples with no fly-ash and fired illite added and illite samples containing 10 wt. %, 20 wt. %, 30 wt. %, and 40 wt. % of fly-ash and 0 wt. %, 10 wt. %, 20 wt. %, and 30 wt. % of fired illite. Addition of fly-ash substantially influences temperature dependences of the DC conductivity and introduces a temperature region with a high conduction activation energy which precedes the dehydroxylation. At the lowest temperatures, the main charge carriers are H+ and OH− ions, while at higher temperatures K+ and Na+ ions also play a role. The phase transformation metaillite -> Al-Si spinel is characterized with a current peak at 940 °C.