Binary common-ion alkali halide mixtures; a uniform description of the liquid and solid state

Abstract

Empirical relations for the thermodynamic excess behaviour of binary common-ion alkali halide mixtures were derived. For the liquid state this gave rise to G E(1)( x, T g) = 0.68 H E(1)( x, T g) and S E(1)( x, T g)=0.32 H E(1)( x, T g)/ T g, and for the solid state G E(1)( x, T)= A(1− T/ (2565 K)) x(1− x)(1+ B(1−2 x)), in which the A parameter can be calculated from relative differences in unit cell volumes of the pure solid components A calc (kJ mol −1) = 11.53(Δ V/ V s)+ 89.40(Δ V/ V s) 2 and the B parameter which is a measure for the asymmetry can be calculated from the A parameter using B = 1.04 × 10 −2( A calc/kJ mol −1). The phase diagrams were calculated and compared with experimental phase diagram data for twenty binary common-ion alkali halide systems that show complete sub-solidus miscibility.