Solid–liquid equilibrium and thermochemical properties of organic eutectic in a monotectic system

Abstract

The phase-diagram of an organic analogue of a metal–non-metal system, involving p-dichlorobenzene–succinonitrile (DCB–SCN), shows the formation of a eutectic and a monotectic with large miscibility gap in the system. The monotectic and the eutectic contain 0.0272 and 0.9429 mole fractions of SCN, respectively, and the critical temperature is 126°C above the monotectic horizontal. The heat of mixing, entropy of fusion, roughness parameter, interfacial energy and excess thermodynamic functions were calculated based on enthalpy of fusion data determined via differential scanning calorimeter method. The interfacial energy shows the applicability of wetting condition, while the microstructures of the pure components, namely, DCB and SCN show faceted and non-faceted morphology, those of the eutectic and the monotectic show peculiar characteristic features.