On the Domain Structure of Rochelle Salt Crystal

Abstract

The effect of the condition of crystallization on the domain pattern was studied by a polarization microscope. Slow crystallization at the temperatures between two Curie points gave domains parallel to the b-axis, whereas above the upper Curie point they were parallel to the c-axis. On raising temperature through the upper Curie point, monoclinicity decreased gradually, without any change of domain width, until the domain pattern disappeared at 24.25°±0.2°C, where a marked pyroelectricity and a maximum of permittivity were observed. The pyroelectric effect continued to exist up to a temperature a little higher. Annealing crystals in the atmosphere of appropriate humidity had no effect on the domain formation. This fact, together with the fact that the crystallization between two Curie points brought about the splitting into domains seems to show that the domain formation is mainly governed by elastic energy rather than electrostatic energy. Explanations of observed phenomena are presented.