CALCULATION OF PHASE DIAGRAMS OF IONIC SYSTEMS FROM FUNDAMENTAL SOLUTION THEORIES∗

Abstract

Fundamental concepts and theories of molten salt solutions appear to be useful in a number of technologies (e.g., high-temperature batteries, fuels cells, aluminum production). A simple but exact cycle permits one to calculate the solubility product of, for example, oxides and sulfides in halide melts. The use of this cycle is well illustrated by calculations related to nuclear fuel processing and to advanced battery technology. For concentrated solutions, the conformal ionic solution theory which is a statistical mechanical perturbation theory is used to calculate the phase diagrams of terna ry systems solely based on information from the lower order (unary and binary) subsystems. Thus, one can numerically generate phase diagrams a priori, reliably extend phase diagrams into unmeasured regions and check the thermodynamic self consistency of published measurements.