Enthalpy and Heat Capacity of Cs-Pb Alloys in Solid and Liquid States

The enthalpy of Cs-Pb system alloys containing 40, 50, 60, and 66.67 at.% Pb have been measured and heat capacity have been determined using high-temperature drop calorimetry method over a temperature range 430-1075 K covering solid and liquid phases. For all alloys, recommended temperature dependences of the studied properties have been developed as well as the enthalpy changes on phase transitions and the liquidus temperature have been determined. The concentration dependence of the heat capacity of Cs-Pb liquid alloys at different temperatures has been constructed, at which the pronounced maximum is observed at a content of 50 at.% Pb. A significant excess of the heat capacity of the studied melts over additive values is revealed. It is shown that the results obtained are consistent with the assumptions in the literature about the formation of structural units with a partially ionic character of interatomic interaction in melts of the Cs-Pb system.