BINARY PHASE-DIAGRAM OF MOLECULAR ALLOYS OF THE CONSECUTIVE EVEN-NUMBERED N-ALKANES N-TETRACOSANE (N-C24H50) AND N-HEXACOSANE (N-C26H54)

The phase diagram of molecular alloys of n-tetracosane (n-C24H50) and n-hexacosane (n-C26H54) has been established by a joint thermodynamic and structural study of twenty five compositions. At ''low temperature s'' it shows the existence of two limited domains of terminal solid so lutions gamma(0)(C-24) and gamma(0)(C-26) and of three orthorhombic in termediate phases, denoted beta'(1), beta '' and beta'(2). With increa sing temperatures, these five solid solutions undergo the same solid-s olid transitions as those observed in the even-numbered and odd-number ed pure n-alkanes and in the system n-docosane (n-C22H46)-n-tetracosan e (n-C24H50), i.e.: gamma(0)(C24) and gamma(0)(C-26) --> Rotator phase alpha-RII (R(3) over barm$) --> Liquid beta'(1), beta'(2) and beta '' --> Rotator phase beta-RI (Fmmm) --> alpha-RII --> Liquid