Electric and electrochemical properties of solid CdBr<inf>2</inf>·4H<inf>2</inf>O in the stage of dehydration

Abstract

The electric conductivity of solid crystallohydrate CdBr2·4H2O was measured at temperatures ranging from room temperature up to 673 K. By means of thermal analysis, infrared spectroscopy and electrochemical methods the conductivity mechanism in certain temperature ranges was assumed. The relatively low conductivity before the beginning of dehydration (≈10-4 S/m, with activation energy of 38.2 kJ/mol)_originates from the movement of H+ ions. With a rise in temperature, the structural changes, due to dehydration, cause a change in the nature of the charge carrier and the conductivity mechanism. Gradual dehydration which starts at ≈310 K activates new charge carriers and causes a sudden increase in the conductivity which remains relatively high (≈1 S/m) up to ≈383 K, until the liberated water, evaporating, leaves the sample. The conductivity of the dehydrated sample is very low (≈10-6 S/m). © 1982.