THE ELECTRICAL-CONDUCTIVITY OF SOLID LIQUID COEXISTING SYSTEMS - ALPHA-AL2O3 POWDER/CACL2 AQUEOUS-SOLUTION SYSTEM

The electrical conductivity and its temperature dependence were investigated for alpha-Al2O3 powder/CaCl2 aqueous solution coexisting system by ac impedance method. The electrical conductivity of the paste unusually decreased with an increase of the volume fraction of the solid phase. The temperature dependence of the electrical conductivity of log sigma vs. 1/T showed a good linear relationship for the system containing the dilute solution as a liquid phase. The activation energy for the electrical conductivity, DELTA-E(a), was determined from the temperature dependence. DELTA-E(a) increases with an increase of the volume fraction and the specific surface area of the solid phase. Also, DELTA-E(a) correlated with the apparent average thickness of the vicinal liquid layer. The dependence deviated from the linear relationship and conformed to the VTF equation with the increase of the concentration of electrolyte. The T(o) parameter of the VTF equation, which means the "ideal" glassy transition temperature, rose with the volume fraction and specific surface area of the solid phase. It is suggested that the solution had a tendency to transform into a "glassy state" in the vicinal liquid layer on the solid surface.