ELECTRICAL-PROPERTIES OF UNUSUAL IONIC MELTS

The paper reviews the advances that have been made in recent years in the understanding of electrical transport in fully ionized molten salts, partly dissociated molecular liquids and liquid ionic stoichiometric alloys like CsAu. Special emphasis is placed on the recently observed temperature and pressure induced gradual transition between the limiting cases of molecular insulators and ionic melts. At supercritical temperatures salts undergo a continuous transition from an insulating vapour to a highly conducting ionic fluid if the density is increased sufficiently. This transition is due to a shift of the ionization equilibrium between molecules and ions, in favour of the ions, with increasing density. Poorly conducting molten salts and polar substances like water and ammonia also become more ionic, and consequently better conductors, at very high pressures. Recent thermodynamic, magnetic and electrical measurements on liquid alloys which are composed of two metallic elements and which are non-metallic at definite stoichiometric compositions are discussed. Special emphasis is placed on the liquid Cs-Au system which resembles in many respects the molten alkalimetal halides. © Taylor & Francis Group, LLC.