Thermodynamics Research Center / ThermoML | Fluid Phase Equilibria

ABSTRACT

Solid-liquid equilibria of (KCl + NH4Cl + H2O) ternary system were investigated and it was found that there were five crystalline regions in the course of crystallization (respectively pure NH4Cl, mNH4Cl*KCl solid solution, NH4Cl*nKCl solid solution, mixed mNH4Cl*KCl and NH4Cl*nKCl solid solution and pure KCl). The type of two solid solutions was determined by analysis of X-ray diffraction (XRD), Fourier transform infra-red (FTIR), lattice constant and density of solid solution crystals. It could conclude that they were limited substitutional solid solutions. Solid solubility (substitutional impurity in solvent) was measured at 25deg C and its variation was in accordance with Vergard s law. Moreover, thermal stability of two solid solutions was compared by TG-DTA. Results showed that both mNH4Cl*KCl and NH4Cl*nKCl shared the property of their mother phase and maintained its individual characteristics.