Semiconductive Colloidal Suspensions with Non-Linear Properties

Abstract

Semiconductive particles in a colloidal suspension, when subjected to an electric polarizing field, form semiconductive chains. Once the suspension is polarized, its conductivity increases with increasing fields because the forces of electrostatic attraction press the individual particles together, thus strengthening the transition contacts along the chains. Both effects result in an over‐all electric non‐linearity that is the subject of extensive investigation. The non‐linear characteristics of such colloidal resistors are oscillographed and described in relation to the polarizing field strength by means of simple formulas based on field coefficients of the first and second order. In addition to a true rectification, resulting from the curved characteristics, a ``pseudo‐rectification'' occurs which corresponds to an average pre‐polarization by stronger alternating fields. The alternating forces of electrostatic attraction assure a high frequency response, so that non‐linear Lissajous‐figures and harmonics, up to radiofrequencies, are produced.