LIQUID ZRF4-BAF2-MF TERNARY-SYSTEMS - CALORIMETRIC DETERMINATION OF EXCESS ENTHALPY .1. M=NA

The enthalpies of formation of liquid BaF2-NaF-ZrF4 ternary mixtures and of the limiting BaF2-NaF and BaF2-ZrF4 binary mixtures were measured by high temperature calorimetry. The mixing procedures used, the "direct drop" or "indirect drop" methods, were selected in accordance with the physico-chemical properties of the systems. The experimental temperatures are close to 1250 K for the different ternary sections, 1307 K for BaF2-NaF, and 1023 K for BaF2-ZrF4. The composition ranges are the widest possible provided that evaporation losses do not exceed 10%. The results obtained are interpreted in terms of ionic complex formation in melts containing zirconium fluoride.