Pre-freezing phenomena investigations in some molten salts

Abstract

Electrical conductance of some molten salts has been measured in the immediate region of the freezing point, to determine the existence of pre-freezing phenomena. Three groups of molten salt were examined:- sodium and potassium chlorides, their nitrate analogues and potassium thiocyanate. No evidence has been found for the existence of pre-freezing phenomena in these salts. The supercooling behaviour of the chlorides and potassium thiocyanate melts is considered to point to the existence of a low temperature non-Arrhenius transport region. A consideration of transport properties of other liquid systems leads us to concur with Angell's theory that transport in all liquids may be related to T o(the ideal glass transition temperature). Further, we conclude that the pre-freezing phenomena observed by Ubbelohde may be more correctly interpreted as the onset of the low temperature non-Arrhenius region.