U${}_3$Si${}_2$ is of interest to the nuclear industry as a candidate fuel material due to its high uranium density and high thermal conductivity. However, it has been observed to react with hydrogen, resulting in material decrepitation. As a result, it is important to understand the thermodynamics of the U${}_3$Si${}_2$-H system. In this study, the thermodynamics of the hydrogen absorption reaction of U${}_3$Si${}_2$ were determined experimentally using Sievert’s gas absorption and related to crystallographic evolution with hydrogen content using X-ray diffraction. Experimentally-determined thermodynamic parameters were compared with results from density functional theory modeling. Results from this study were also compared with those determined in previous work. Sievert’s gas absorption results were used to develop the pressure-composition-temperature (PCT) curves of the U${}_3$Si${}_2$-H system. It was found that the hydride phase exhibited a maximum stoichiometry between U${}_3$Si${}_2$H${}_{1.8}$ and U${}_3$Si${}_2$H${}_2$. The two-phase region for hydride formation from U${}_3$Si${}_2$ exhibited a miscibility gap with a critical temperature between 623 and 673 K, as calculated from the PCT curves. Analysis of the PCT curves also showed that both the enthalpy and entropy of the hydrogen absorption reaction increased with hydrogen content but were lower than the values for uranium trihydride formation from uranium metal. The enthalpy of reaction for hydrogen absorption was calculated to range between -86.9 and -94.8 kJ mol${}^{-1}$, while the entropy of reaction was calculated to range between 101.9 and 138.8 J mol${}^{-1}$ K${}^{-1}$. DFT modeling of the thermoydnamic stability of the U${}_3$Si${}_2$ hydride phases yielded a decomposition temperature of U${}_3$Si${}_2$H${}_2$ of approximately 600 K, which was consistent with the experimental results. Similarly, the DFT-calculated enthalpy and entropy of reaction to form U${}_3$Si${}_2$H${}_{1.5}$ were determined to be -106.5kJ mol${}^{-1}$ and 121.8J mol${}^{-1}$ K${}^{-1}$, respectively, which were both in close agreement with the experimentally-determined values.

你${}_3$硅${}_2$由于其高铀密度和高导热性，核工业对作为候选燃料材料感兴趣。然而，已经观察到它与氢反应，导致材料爆裂。因此，了解 U 的热力学非常重要。${}_3$硅${}_2$-H 系统。在本研究中，U 的吸氢反应的热力学${}_3$硅${}_2$使用 Sievert 的气体吸收实验确定，并与使用 X 射线衍射的氢含量有关的晶体演化。实验确定的热力学参数与密度泛函理论建模的结果进行了比较。这项研究的结果也与先前工作中确定的结果进行了比较。Sievert 的气体吸收结果用于开发 U 的压力-成分-温度 (PCT) 曲线${}_3$硅${}_2$-H 系统。发现氢化物相在 U${}_3$硅${}_2$H${}_{1.8}$ 和你${}_3$硅${}_2$H${}_2$. 从 U 形成氢化物的两相区域${}_3$硅${}_2$从 PCT 曲线计算出的临界温度在 623 和 673 K 之间表现出混溶性差距。PCT 曲线的分析还表明，氢吸收反应的焓和熵都随着氢含量的增加而增加，但低于从金属铀形成三氢化铀的值。计算出的吸氢反应焓在 -86.9 和 -94.8 kJ mol 之间${}^{-1}$，而计算的反应熵在 101.9 和 138.8 J mol 之间${}^{-1}$ 钾${}^{-1}$. U 热力学稳定性的 DFT 建模${}_3$硅${}_2$ 氢化物相产生的分解温度为 U${}_3$硅${}_2$H${}_2$约 600 K，与实验结果一致。类似地，DFT 计算的反应焓和熵形成 U${}_3$硅${}_2$H${}_{1.5}$ 被确定为 -106.5kJ mol${}^{-1}$ 和 121.8J 摩尔${}^{-1}$ 钾${}^{-1}$，分别与实验确定的值非常一致。