The Electronic Properties of Metal Solutions

Abstract

The introduction of sodium metal into anhydrous liquid ammonia produces an intensely coloured blue solution in which localised excess electrons, sodium cations, and various agglomerates of these species co-exist in equilibrium. With increasing metal concentration the system transforms into a bronze metallic conductor. In the transitional range, cooling of the (homogeneous) sample can give rise to a remarkable liquid-liquid separation in which both dilute (blue) and concentrated (bronze) phases co-exist. The apparent experimental simplicity of this system which permits the localisation of the fundamental unit of electrical change in dilute solutions, and its itineracy in concentrated solutions, has attracted a considerable amount of study from both chemists and physicists during the last 100 years.

In this article we discuss the recent advances made not only in the study of metals in liquid ammonia, but also in solutions of metals in various other solvents, for example, amines and ethers. The review attempts to cover the properties of metal solutions in the dilute and concentrated ranges, as well as the nature of the Metal-non-Metal transition in these systems.