Molar Volume and Electrical Conductivity Measurements in the Ternary Molten Salt System blaCI-CsCI-MnCI, I. Molar Volumes

Densi t ies in the ternary system NaC1-CsCl-MnC12 have been measured by the Archimedian technique at temperatures varying between 550 ~ and 1050~ The molar volumes of the solutions show positive deviations from additivity which become more pronounced in the CsCl-rich melts. The behavior of the sys tem is explained in terms of a complex ion model based on the presence of NaMn2C14 and Cs~MnC14 complex species in these melts. It is shown theo-retically and proven experimentally that the molar volumes in the ternary system may be predicted by the simple express ion V,~.3 = tV1 ~ + (I-- t)V,= where t = Xcscl/(XN,.ci + Xcscl), Iq.28 is the molar volume of the ternary system, and V, ~ and Vla are the molar " volumes of the binary system MnC12-CsC1 and MnCI~-NaCI, 'respectively, having the same MnC12 content as the ternary. This expression is valid along a composition path for which ~ / = con-stant, where y = 1-- XMnc~. It is of interest o note that the t-fraction aver