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.

中文翻译：

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三元系统 (CsNO3 + NH4NO3 + H2O) 在 (298.15 和 348.15) K 和 101.325 kPa 下的固液相平衡

本文采用等温溶解平衡法分别测量了三元体系(CsNO3 + NH4NO3 + H2O)在298.15、348.15 K和101.325 kPa下的溶解度和密度，以及这两个温度下的相图和密度-组成图第一次建立在实验数据的基础上。在这两种温度下的三元体系中，都有一个不变点，两条溶解度等温线，以及两个分别对应于硝酸铯（CsNO3）和硝酸铵（NH4NO3）的结晶区。两种温度下的相图属于简单型咸水体系，既没有形成复盐也没有形成固溶体。随着两种温度下溶液中硝酸铵浓度的增加，溶液的密度逐渐增加，在不变点处先达到最大值，然后逐渐减小。此外，基于电解质密度的经验方程，两种温度下的密度计算值与实验数据吻合良好。