Theoretical Investigation of Ferroelastic Phase Transition of Pure and Mixed Alkali Cyanide Systems by the Elastic Dipole Model. I. The Cubic‐Orthorhombic Phase Transition of Pure Potassium Cyanide

Abstract

AbstractThe kinetics of elastic ordering of KCN controlled by a thermally activated process is studied by considering the interaction between elastic CN− dipoles. The lattice constants obtained and reorientational activation energy of dipoles in the elastically ordered lattice agree quantitatively with experiments. The calculation indicates that the orientation ordering of elastic dipoles is induced by the strain field due to ordering alignment of dipoles. The elastic interaction between close neighbors of dipoles has little influence. The first‐order character of the phase transition is obtained, and it is found that an initial degree of order depending on the temperature is necessary to start the ordering process. It is concluded that this corresponds to the nucleation process of the first‐order phase transition.