Modeling and Calculation of the LiF−NaF−MF₃ (M = La, Ce, Pu) Phase Diagrams

The ternary systems LiF−NaF−LaF 3 and LiF−NaF−CeF 3 have been experimentally analyzed and thermodynamically assessed. Two models were used and compared to describe the excess Gibbs terms of the binary subsystems. One was a regular polynomial description of the excess terms, the other a quasichemical in the quadruplet approximation. In both cases, a fine agreement with the experimental data was achieved, after asymmetrical extrapolation from the binary to the ternary systems. The binary systems of the related actinide system LiF−NaF−PuF 3 were assessed, making use of experimental data known from the literature. The lanthanide systems served as a proxy for LiF−NaF−PuF 3 to calculate the ternary phase diagram.