Dilatometric Study of the Phase Transition of Quasi-One-Dimensional Ferroelectric CsH₂PO₄

Abstract

All of the components of the strain tensor x_i (i=1, 2, 3 and 5) due to the temperature change have been measured for CsH₂PO₄ in a wide temperature range including the transition point. These strain components, except x₃, show anomalous temperature dependences which are hard to explain by the usual phenomenological theory. The quasi-one-dimensional Ising model by Carvalho and Salinas was extended to compressible cases. It is found that the extended model can give a quantitative explanation of the experimental results.