The stable phase equilibria of the ternary system MgBr₂ + SrBr₂ + H₂O at 288 and 308 K were studied with the isothermal dissolution equilibrium method. The compositions of solutions and solid phases have been determined and the equilibrium solid phases at the invariant points were identified with the aid of the X-ray diffraction method. The phase diagrams of this system at 288 and 308 K were both constructed in terms of experimental results. Two stable phase diagrams show that this system is hydrate type I at two temperatures without formation of a solid solution or complex salt. Both the phase diagrams are composed of one invariant point, two univariate curves, and two crystallization regions (SrBr₂·6H₂O and MgBr₂·6H₂O). The equilibrium solid phases of the invariant point at 288 and 308 K are both SrBr₂·6H₂O and MgBr₂·6H₂O, respectively. Combining the Pitzer single-salt parameters of MgBr₂ and SrBr₂ reported in the literatures, the unreported mixing ion-interaction parameters θ_Mg,Sr and Ψ_Mg,Sr,Br at 288 and 308 K were fitted with the measured values in this study using the Pitzer equations. The agreement between the experimental values and calculated results in the ternary system MgBr₂ + SrBr₂ + H₂O at 288 and 308 K shows that the parameters fitted with solubilities are reliable.

中文翻译：

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三元体系 MgBr ₂ + SrBr ₂ + H ₂ O 在 288 和 308 K 中溶解度的测量和预测

用等温溶解平衡法研究了三元体系MgBr ₂ + SrBr ₂ + H ₂ O在288和308 K下的稳定相平衡。确定了溶液和固相的组成，并借助X射线衍射法确定了不变点处的平衡固相。该系统在 288 和 308 K 的相图都是根据实验结果构建的。两个稳定相图表明该系统在两个温度下为 I 型水合物，没有形成固溶体或复盐。两个相图均由一个不变点、两条单变量曲线和两个结晶区（SrBr ₂ ·6H ₂O和MgBr ₂ ·6H ₂ O)。288K和308K不变点的平衡固相分别为SrBr ₂ ·6H ₂ O和MgBr ₂ ·6H ₂ O。结合文献报道的 MgBr ₂和 SrBr ₂的 Pitzer 单盐参数，将未报道的混合离子相互作用参数 θ _Mg,Sr和 Ψ _Mg,Sr,Br在 288 和 308 K 与本研究中的测量值进行拟合使用 Pitzer 方程。三元体系MgBr ₂ + SrBr ₂ + H ₂实验值与计算结果的一致性O 在 288 和 308 K 表明符合溶解度的参数是可靠的。