Dilatometric Study on Monoclinic Crystals of Ferroelectric TGS Down to Cryogenic Temperature Region

Abstract

We have further developed the clip-type strain gauge dilatometer in order to measure an angular deformation by applying the cosine theorem. In this research, not only a linear thermal expansion along three crystallographic axes but also a monoclinic angle β of ferroelectric TGS in the monoclinic system were measured below 380 K down to the cryogenic temperature region. Each of these components showed a clear bend and a typical feature of the second order transition at the Curie temperature. On the other hand, the volume thermal expansion did not show a big change at the Curie temperature.