A Simple Dilatometer Technique for Phase Transition Study in Crystals

Abstract

One of the techniques for the phase transition investigation in crystals is the measurement of thermal expansion, since it is correlated with several thermodynamic properties. A new simple dilatometer is here reported. It is based on the principle of measuring the expansion of a needle-shaped material in terms of the change in rotational angle of a reflecting surface with the help of a spectrometer vernier scale. It has an overall sensitivity of 1 to 2 × 10^-6/°C. This dilatometer has been successfully employed in the phase transition study of ferroelectric triglycine sulfate and potassium nitrate. Our measurements of transition temperatures and thermal expansion of these materials are in good agreement with the values reported in the literature.