The heat capacity and lattice parameters of europium fluoride EuF_2.16 and (SrF₂)_0.5(EuF_2.16)_0.5 solid solution are experimentally investigated at temperatures 2–300 K. The revealed anomalies in the heat capacity are due to magnetic phase transition and disorder in fluorides crystal structures. The dependencies studied were analyzed using the Debye–Einstein approximation, taking into account the influence of the magnetic phase transition, two-level systems, and anharmonicity of lattice vibrations on their thermodynamic properties. We determined the parameters of the Debye and Einstein models – the characteristic temperatures as well as the magnitudes their respective contributions to the overall thermodynamic characteristics, the parameters characterizing crystal structure disorder, and the exchange parameters characterizing interaction in magnetic subsystems of fluorides. Dependences studied for solid solution deviate from the additive values. We further established that the mechanisms causing these are based on the disorder in the crystal structures of europium fluoride and its solid solution.

氟化铕 EuF _2.16和 (SrF ₂ ) _0.5 (EuF _2.16 ) _0.5的热容和晶格参数固溶体在 2-300 K 温度下进行实验研究。揭示的热容量异常是由于磁性相变和氟化物晶体结构的无序。使用 Debye-Einstein 近似分析了所研究的相关性，同时考虑了磁相变、两能级系统和晶格振动的非谐性对其热力学性质的影响。我们确定了德拜和爱因斯坦模型的参数——特征温度以及它们各自对整体热力学特性的贡献、表征晶体结构无序的参数以及表征氟化物磁性子系统中相互作用的交换参数。研究的固溶体相关性与附加值不同。我们进一步确定导致这些的机制是基于氟化铕及其固溶体的晶体结构的无序。