Phase diagram and thermochemical properties of organic eutectic in a monotectic system

The phase diagram of a binary organic system involving diphenyl and succinonitrile shows the formation of a eutectic (0·968 mole fraction of succinonitrile) and a monotectic (0·074 mole fraction of succinonitrile) with a large miscibility gap in the system, the upper consolute temperature being 53·5°C above the monotectic horizontal. From the enthalpy of fusion of the pure components, the eutectic and the monotectic, determined by the DSC method, the enthalpy of mixing, Jackson’s roughness parameter, interfacial energy, size of the critical nucleus and excess thermodynamic functions were calculated.