Electrical resistivity of porcelain in relation to constitution

The electrical resistivity of porcelain samples has been measured from room temperature to 1200 degrees C and it was found to depend on the concentration of the phases as well as the size and size-distribution of mullite crystals. The resistivity of porcelain was found to decrease with increase in amount, size and asymmetry of size-distribution of mullite crystals but increase with increase in quartz, cristobalite and glass content. Irrespective of constitution, resistivity of porcelain decreased with rise in temperature from about 10(13) ohm-cm at room temperature to about 10(4) ohm-cm at 1200 degrees C. The change in electrical resistivity of porcelain was primarily controlled by the defect structure of mullite and the composition and viscosity of the glassy phase. (C) 1998 Elsevier Science Limited and Techna S.r.l. All rights reserved