The isoperibolic calorimetry method was employed to determine, for the first time, the partial and integral mixing enthalpies for melts in the Eu–Ge system over the entire composition range at 1200 K and 1370–1440 K. The minimum mixing enthalpy for these melts was –49.1 ± 4.4 kJ/mol and was shown by the alloy with x_Ge = 0.45, while \(\Delta {\overline{H} }_{{\text{Eu}}}^{\infty }\) = –145.7 ± 22.3 kJ/mol and \(\Delta {\overline{H} }_{{\text{Ge}}}^{\infty }\) = –166.8 ± ± 19.8 kJ/mol at 1400 ± 3 K, correlating with the solid-state behavior of these melts. This allows categorizing these melts within the series of the Ge–Ln (lanthanide) systems and justifying the thermodynamic properties of melts in the Eu–Ge system, in particular, and in the Ge–Ln system, in general. Using the thermochemical properties for melts in the Eu–Ge system, the ideal associated solution model was employed to optimize and calculate the Gibbs energies, enthalpies, and entropies of formation for the melts, associates in melts, and intermetallics. A large number of associates, especially EuGe, formed in the studied melts because of the highest probability of collision between two dissimilar atoms in liquid alloys. The maximum mole fraction of the EuGe associate reached 0.48 and those of Eu₃Ge, Eu₂Ge, EuGe₂, and EuGe₃ were 0.2, 0.26, 0.24, and 0.26, respectively. The activities of components in melts of the Eu–Ge system showed substantial negative deviations from the ideal solution, correlating with our thermochemical properties. This all indicated strong interactions between dissimilar atoms in melts of the Eu–Ge system, likely involving the transfer of valence electrons of europium to the 4p orbital of germanium. The ΔG values over the entire composition range were greater than ΔH, with ΔG_min = –28.8 kJ/mol at x_Ge = 0.45. Moreover, the ΔG function was also almost symmetrical because of the entropy contribution (mixing entropy of the studied melts was negative, and ΔS_min = –15.0 J/mol K at x_Ge = 0.45). The calculations based on the ideal associated solution model also established that the \(\Delta {\overline{H} }_{{\text{Eu}}}^{\infty }\) values for melts in the Eu–Ge system increased insignificantly with temperature, while \(\Delta {\overline{H} }_{{\text{Ge}}}^{\infty }\) increased more substantially. This might be due to the break of covalent bonds between germanium atoms. Complete information on the thermodynamic properties of all phases was obtained, enabling a thermodynamic description of the Eu–Ge system for the first time.

首次采用等周量热法测定了 Eu-Ge 体系熔体在 1200 K 和 1370-1440 K 整个成分范围内的部分和整体混合焓。这些熔体的最小混合焓为–49.1 ± 4.4 kJ/mol，由x _Ge = 0.45的合金显示，而\(\Delta {\overline{H} }_{{\text{Eu}}}^{\infty }\) = – 145.7 ± 22.3 kJ/mol 和\(\Delta {\overline{H} }_{{\text{Ge}}}^{\infty }\) = –166.8 ± ± 19.8 kJ/mol 在 1400 ± 3 K 时，与这些熔体的固态行为相关。这允许将这些熔体分类在Ge-Ln（镧系元素）系统系列中，并证明Eu-Ge系统中熔体的热力学性质，特别是在Ge-Ln系统中，一般而言。利用Eu-Ge体系中熔体的热化学性质，采用理想关联溶液模型来优化和计算熔体、熔体中的共轭物和金属间化合物的吉布斯能、焓和形成熵。由于液态合​​金中两种不同原子之间的碰撞概率最高，因此在所研究的熔体中形成了大量的共晶，尤其是 EuGe。EuGe缔合物的最大摩尔分数达到0.48，Eu ₃ Ge、Eu ₂ Ge、EuGe ₂和EuGe ₃的摩尔分数分别为0.2、0.26、0.24和0.26。Eu-Ge 系统熔体中组分的活性与理想溶液存在显着的负偏差，这与我们的热化学性质相关。这一切都表明，Eu-Ge 体系熔体中的不同原子之间存在强烈的相互作用，可能涉及铕的价电子转移到锗的 4p 轨道。整个成分范围内的Δ G值大于 Δ H，其中 Δ G _min = –28.8 kJ/mol（x _Ge = 0.45）。此外，由于熵的贡献，Δ G函数也几乎是对称的（所研究熔体的混合熵为负，并且在x _{Ge = 0.45 时 Δ} S _min = –15.0 J/mol K ）。基于理想关联解模型的计算还确定了Eu-Ge 体系熔体的 \(\Delta {\overline{H} }_{{\text{Eu}}}^{\infty }\)值随着温度的增加不显着，而\(\Delta {\overline{H} }_{{\text{Ge}}}^{\infty }\)增加更为大幅度。这可能是由于锗原子之间的共价键断裂造成的。获得了所有相热力学性质的完整信息，首次实现了Eu-Ge系统的热力学描述。