Electrical Conductivity and Dielectric Dispersion Phenomena of Concentrated TiO₂ Suspensions

ISSN： 0021-9797

Source： Journal of Colloid and Interface Science, Vol.228, Iss.2, 2000-08, pp. : 423-427

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Abstract

The complex conductivity of concentrated TiO₂ suspensions (up to 50 vol%) was measured over a large frequency range (1 MHz–1.8 GHz), as a function of grain volume content. These measurements highlight relaxation phenomena in the intermediate frequency range, which are associated with the dispersed powder. These phenomena were previously noted in O'Brien's theoretical developments. A quantitative data analysis was made, in terms of time constant distribution, using the CONTIN software, from Provencher. As a result, a complex process is highlighted, including two main mechanisms in different ranges of time constants. Particularly, we showed good agreement between the higher frequency mechanism and the O'Brien theory. From Dukhin's λ ratios, which are ratios of grain surface to bulk electrolyte conductances, we calculated the electrolyte conductivity as a function of powder concentrations. At higher powder concentrations, these values are different from those measured with centrifuged liquids.