The Effect of Pressure on the Electrical Conductivity of the Molten Halides of Mercury and the Molten Iodides of Cadmium, Gallium and Indium

Abstract

Abstract The electrical conductivities of molten HgCl2, HgBr2, Hgl2, Cdl2, Gal3 and InI3 were measured to pressures of 1 GPa (10 kbar), using a heated pressure vessel pressurised with argon. Additionally, the conductivities of CdI2 and HgCl2 were measured from 2 to 6 GPa, using a tetrahedral anvil apparatus. In every case the conductivity rose with pressure initially, and this is thought to be due to an increase in the degree of self-ionisation of the liquid. For CdI2 and Hgl2 a maximum was observed in the conductivity isotherm below 1 GPa, and for HgCl2 the conductivity fell with pressure from 2 to 6 GPa, implying that a maximum exists between 1 and 2 GPa. At the maximum the degree of ionisation approaches unity, and there is a balance between the competing effects of pressure in increasing the degree of ionisation and in reducing the ionic mobilities.