Magnetic susceptibility of alkali n -butyrates and isovalerates near their melting points

Abstract

Various physical properties of alkali carboxylates can be used to study precursor effects immediately below or above their melting points. The present paper describes unusual pre-transition behaviour observed in the magnetic susceptibility of molten n -butyrates and isovalerates. This takes the form of a transitory enhancement of diamagnetic susceptibility, by nearly 10% in some cases, when the isotropic melt is cooled through the clearing point and into the mesophase region while a magnetic field (up to 1 T(10 4 G)) is applied. No corresponding changes are observed on taking the salt through the same temperature range but in the inverse direction. Again, no corresponding change is observed with an alkali carboxylate which shows no mesophase melting transition. Present findings can be accounted for on the assumption of cluster formation in the molten salts as these approach their upper melting points, which is also indicated by other evidence. The (transient) enhancement of molecular diamagnetism in this region of temperature may also indicate transient perturbations in the actual cation-anion binding near the transition temperature.