Volume Rectification in Zincite

Abstract

THE experiments of Khastgir and Das Gupta¹ showed that when carborundum, zincite or silicon was placed between two mercury electrodes giving large contact areas, there was considerable rectification, while similar experiments with symmetrical crystals like iron pyrites, magnetite, galena, et., showed no rectification when the surface effects were eliminated. These experimental results suggested that the rectification observed in polar crystals such as carborundum, zincite or silicon with electrodes of large contact-areas should be associated with the asymmetry in the structure of these crystals. The experiments of Deaglio² with two different thicknesses of carborundum having the same contactareas on the opposite faces, mechanically scraped plane and platinized, showed that rectification per centimetre thickness, as indicated by the static characteristic curves, was the same. This proved that the observed rectification in carborundum was definitely associated with the volume of the crystal and not with the area in contact with the electrodes. The object of the present communication is to report some experimental results with zincite, which has shown similar rectification depending on the volume of the crystal. A theoretical treatment is also given of the origin of volume rectification in polar crystals.