STRUCTURAL EVOLUTIONS OF N-DOCOSANE AND N-TRICOSANE MIXTURES AT ROOM-TEMPERATURE

A structural study of odd and even numbered n-alkanes (C-n) binary mix tures (n-docosane-n-tricosane) was carried out on powder samples using Guinier de Wolff camera with increasing concentration of n-tricosane at room temperature. Instead of what it is reported in the literature, these molecular alloys do not form an orthorhombic continuous homogen eous solid solutions from n-docosane to n-tricosane at low temperature . In contrary, the mixing of these alkanes lead to two terminal solid solutions gamma(0)(nC(22)) and beta(0)(nC(23)) and two orthorhombic in termediate solid solutions denoted beta(1)' and beta(1) ''. These phas es have been analysed by X-ray diffraction and their lattice parameter s were determined. Moreover, the existence domains of all the phases c ited have been precised. It appears that their appearance sequence are in agreement with the general rule relative to the thermodynamical an d structural behaviour of two consecutive n-alkanes previously publish ed. (C) 1997 Elsevier Science B.V.