Features of non-congruent phase transition in modified Coulomb model of the binary ionic mixture

Abstract

Non-congruent gas-liquid phase transition (NCPT) have been studied in modified Coulomb model of a binary ionic mixture C(+6) + O(+8) on a \textit{uniformly compressible} ideal electronic background /BIM($\sim$)/. The features of NCPT in improved version of the BIM($\sim$) model for the same mixture on background of \textit{non-ideal} electronic Fermi-gas and comparison it with the previous calculations are the subject of present study. Analytical fits for Coulomb corrections to EoS of electronic and ionic subsystems were used in present calculations within the Gibbs--Guggenheim conditions of non-congruent phase equilibrium.Parameters of critical point-line (CPL) were calculated on the entire range of proportions of mixed ions $0<X<1$. Strong "distillation" effect was found for NCPT in present BIM($\sim$) model. Just similar distillation was obtained in variant of NCPT in dense nuslear matter. The absence of azeotropic compositions was revealed in studied variants of BIM($\sim$) in contrast to explicit existence of azeotropic compositions for the NCPT in chemically reacting plasmas and in astrophysical applications.