IMPEDANCE SPECTROSCOPY OF COLLOIDS

We present a four-electrode dielectric spectrometer, particularly deve loped for measuring relaxation characteristics in the impedance of col loidal dispersions. The instrument is optimized for covering the frequ ency range from approximately 500 Hz to 500 kHz. The set-up consists o f a cell connected to a signal-Processing unit and a commercial freque ncy response analyser. The four-electrode design avoids effects of ele ctrode polarization. The electronic circuitry is optimized for measuri ng small differences between the impedances of samples and blanks, eac h with extremely small phase angle values (of the order of 0.0001 rad) .