Thermodynamic properties of lanthanide metals in liquid bismuth

Thermodynamic quantities of La, Gd, Tb, and Dy in liquid bismuth were exper imentally determined by electromotive force (EMF) measurement using a cell consisting of molten alkaline chloride and liquid bismuth. Excess Gibbs ene rgy changes and activity coefficients were determined at varying concentrat ions and temperatures. Through their temperature dependence, corresponding enthalpy changes and entropy changes were determined. The excess enthalpy c hanges of La, Gd, Tb, and Dy in liquid bismuth in a temperature range from 850 to 1100 K were evaluated to be, -271.54 +/- 2.31, -202.25 +/- 1.80, -19 9.83 +/- 0.55, and -193.80 +/- 0.99 kJ/mol, respectively. The systematic va riation of excess enthalpy change of lanthanides along the 4f-series was di scussed. As a result, it was found that the excess enthalpy changes of La, Gd, Tb, Dy, and Er are likely to depend linearly on the 2/3 power of their metallic volume. (C) 2001 Elsevier Science B.V. All rights reserved.