Chemical potentials and related thermodynamics of liquid Na–Cs alloys

Data on the temperature and composition dependence of the chemical potential of Na in liquid Na–Cs alloys, obtained from an electrochemical cell, are reported. A variety of thermodynamic parameters are calculated. In particular the long-wavelength limit of the concentration correlation function is calculated and used to rule out the existence of Na2Cs. Rather, it is shown that there are long range fluctuations (as at a phase separation) in the vicinity of xNa = 0.80. This incipient phase separation must then be the cause of anomalies in acoustic and other properties reported in the Na-rich portion of the phase diagram.