Thermal Expansion of Triglycine Sulphate

Abstract

Matthias, Miller and Remeika¹ were the first to observe that triglycine sulphate becomes ferroelectric below 47° C. The dielectric properties and the specific heat of this crystal have been studied through the transition temperature by Hoshino, Mitsui, Jona and Pepinsky². The observed variation of the dielectric properties as a function of temperature in this crystal shows that the transition is of second order. Hoshino et al. concluded that the anomaly is not of the λ-type, since their specific heat – temperature curve showed only a hump. It was decided to investigate the thermal expansion of this crystal as it might throw some light on the nature of the transition.