Effect of the Alkaline Metal Cations on the Electrical Conductivity of the Molten Cryolites (K3AIF6, Rb3AIF6, and Cs3AIF6)

The electrical conductivity of molten K(3)AIF(6), Rb(3)AIF(6), Cs(3)AIF(6), and CsF was measured at various temperatures using a pyrolytic boron nitride tube, platinum-rhodium alloy electrode, and alternating current impedance method. The electrical conductivity of molten K(3)AIF(6) was found to be 2.64 S.cm(-1) at 1273 K The electrical conductivity of molten Rb(3)AIF(6) was found to be 2.06 S.cm(-1) at 1273 K. The conductivity of molten Cs(3)AIF(6) at the same temperature is 1.36 S-cm(-1) because the conductivity of CsF at 1273 K was found to be 2.57 S.cm(-1). The electrical conductivity values steadily drop from lithium fluoride/fluoroaluminate through sodium and potassium to cesium fluoride/fluoroaluminate. This fall in conductivity is probably because of the increase in the size and mass of the cations (activation energy increases with decreasing conductivity).