Solid Rotator Phase in Polar Liquids

Abstract

Rotational behavior of five liquids having nearly spherical molecules has been studied by measuring their dielectric constant over a wide temperature range extending from liquid state to the solid state. Nitrobromoform and trimethylacetealdehyde show the existence of solid rotator phases. Different criteria of classifying polar liquids into two classes, Class I, not having a solid rotator phase and, Class II, having a solid rotator phase, have been discussed and 24 liquids have been examined in the light of these classifications. It has been shown that for Class II liquids x (the ratio of enthalpies from the dielectric relaxation and viscosity processes) is less than 0.45 and for Class I liquids x is greater than 0.55. The liquids which have x lying between 0.45 and 0.55 may show free rotation or may have a restricted rotation in the solid phase.