Re-examination of the Thermal Expansion of the Ferroelectric Triglycine Sulfate

The temperature dependence of the thermal expansion coefficients of a single crystal of ferroelectric triglycine sulfate was measured through the Curie point by both X-ray diffraction and dilatometric methods. The results of the measurements were compared with the corresponding data independently obtained by Ezhkova et al. and by Ganesan. Thermal expansion coefficient vs . temperature curves obtained by the X-ray measurement and by the dilatometric method are in good agreement with each other and no effect of the radiation damage (as reported by Ganesan) was found. The discrepancies among the results measured by various workers may be explained by the consideration of the accuracy of measurements. It is concluded that the essential feature of the thermal expansion of triglycine sulfate is not affected by a moderate dosage of X-rays.