Measurement of chemical activities of rare earths (RE: Ce, Pr, Sm and Eu) in cadmium alloy

Abstract Activity of rare earth (RE) elements, Ce, Pr, Sm and Eu is measured in each of the cadmium rich binary alloys of RE, by making use of a molten salt based electrochemical cell. The binary alloy consists of a mixture of cadmium rich intermetallic compound and a liquid phase of known composition. Four independent cells are constructed; one for each of the rare earth elements and electromotive force (EMF) is measured as a function of temperature for each cell, respectively. Partial molar Gibbs energy of these rare earth metals in liquid cadmium is derived from the EMF output over a temperature range. Gibbs energy of formation of CeCd 11 , PrCd 11, SmCd 6 and EuCd 11 are deduced from the measured EMF values and the reported literature data on the solubility of rare earth elements in liquid cadmium.