Liquid Metals

Anomalies in the Thermophysical Properties of Liquid Metals

In anomalous liquids, the melting curve decreases in some pressure range, indicating that the melt is denser than the solid. The best known example is ice floating on water. This anomaly is sometimes accompanied by an anomaly in the temperature dependence of the sound velocity which increases with temperature until a maximum is reached and then decreases as normal. The melting curve anomaly can be explained by the existence of a liquid-liquid phase transition of first order, e.g. as has been argued for water. An additional well known anomaly occurs in the temperature dependence of the density in some liquids, e.g. water and tellurium, where the density increases with temperature to a maximum. The physics underlying these anomalies in liquid metals and their inter-relations are still poorly understood.

It has long been known that many liquid elements in groups 14-16 display anomalous behavior. Experimental studies of liquid metals in these groups show that the thermo-physical properties do not evolve smoothly, but instead there exists a fine structure in their evolution over phase space, indicative of possible underlying transitions. Previously, we have identified a transition in liquid bismuth, which may be a liquid-liquid phase transition and have correlated it with a change in the structural temperature dependence. In preliminary studies on liquid antimony, we identified a correlation of the temperature dependence of the structure with the anomalous maximum in the sound velocity curve. The main aim of the present project is to explore the origins of the anomalies in the physical properties of selected pure liquid metals and their alloys in groups 14-16.