COMPONENTS OF THE MEASURED SURFACE-CHARGE OF LOW-TEMPERATURE CERAMIC OXIDES

This paper contains an analysis of the interfacial behaviour of samples of monoclinic zirconia. The oxide powder was obtained by calcining a hydrothermal precursor at 200-degrees-C. Results of surface charge determinations are elaborated to yield total capacitance values which, in turn, are analyzed on the basis of Parsons and Zobel (P-Z) plots (R. Parsons and F.G.R. Zobel, J. Electroanal. Chem., 9 (1965) 333). The aptitude of selecting either a planar or a spherical geometry for the diffuse double layer is discussed. Analysis of the results in P-Z coordinates indicates that samples subjected to the "routine" overnight conditioning in the solution present only effects due to simple diffuse double layer charge compensation. In the case, instead, of samples conditioned for a longer time (143 h), different components of the surface charge become apparent. Phenomena related to bulk penetration of the base electrolyte are suggested to occur in the latter case.