Structural Behavior of n-Tricosane and n-Pentacosane Mixtures at 20°C

The study of the n-tricosane (n-C23H48): n-pentacosane (n-C25H52) mixtures was carried out using X-ray analyses. In spite of what is found in the literature, the X-ray diffraction results show the presence of six orthorhombic solid solutions when the molar concentration in n-pentacosane increases: three terminal solid solutions, denoted beta(0)(C-23), beta'(0)(C-23) and beta(0)(C-25), isostructural with n-tricosane and n-pentacosane structures and three orthorhombic intermediate phases, denoted beta "(1), beta' and beta "(2). On the basis of powder X-ray patterns, the phases beta "(1) and beta "(2) are indistinguishable and they are isostructural with the solid solution beta " of the binary systems n-C22H46: n-C24H50 and n-C24H50: n-C26H54. The orthorhombic intermediate solid solution beta' is also isostructural with the phases beta'(1) and beta'(2) of the binary systems n-C22H46: n-C24H50 and n-C24H50: n-C26H54. The six solid solutions ranges are determined by the X-ray patterns examination of twenty seven mixtures at 20 degrees C.