Molar Volume and Surface Tension of Molten LaCl3-KCl Mixtures

M olar volumes and surface tensions o f m olten L aC l3-KCl m ixtures were m easured by dilatom etry and the m axim um bubble pressure m ethod, respectively. The m olar volum e isotherm s were found to deviate positively from additiv ity over the whole com position range, with the m axim um deviation at ca. 30 mol% L aC l3. At the same concentration the isotherm s o f surface tension at tem peratures below 950 °C show a m inim um . Surface energy o f m ixing per unit area calculated from the surface tensions shows a large negative excess at the corresponding com position. These observations are related to the existence o f LaClg“ in the KCl-rich melt.