Solid-Liquid Phase Equilibria of the Ternary System (CsNO3 + NH4NO3 + H2O) at (298.15 and 348.15) K and 101.325 kPa

In this paper, the solubilities and the densities of the ternary system (CsNO3 + NH4NO3 + H2O) at 298.15 and 348.15 K and 101.325 kPa were measured using the isothermal dissolution equilibrium method, and the phase diagrams and density versus composition diagrams at these two temperatures were established on the basis of experimental data for the first time. In the ternary system at both temperatures, there are all one invariant point, two solubility isotherm curves, and two crystallization zones corresponding to cesium nitrate (CsNO3) and ammonium nitrate (NH4NO3). The phase diagram at two temperatures belongs to the simple-type of salt–water system, neither double salt nor solid solution were formed. With increasing of the concentration of ammonium nitrate in solution at the two temperatures, the density of the solution is increased gradually, firstly to reach the maximum value at the invariant point, and then decreased gradually. Moreover, on the basis of empirical equations of density of the electrolytes, the calculated values of densities at the two temperatures agree well with the experimental data.