Zircon (ZrSiO₄, I4₁/amd) can accommodate actinides, such as thorium, uranium, and plutonium. The zircon structure has been determined for several of the end-member compositions of other actinides, such as plutonium and neptunium. However, the thermodynamic properties of these actinide zircon structure types are largely unknown due to the difficulties in synthesizing these materials and handling transuranium actinides. Thus, we have completed a thermodynamic study of cerium orthosilicate, stetindite (CeSiO₄), a surrogate of PuSiO₄. For the first time, the standard enthalpy of formation of CeSiO₄ was obtained by high temperature oxide melt solution calorimetry to be −1971.9 ± 3.6 kJ/mol. Stetindite is energetically metastable with respect to CeO₂ and SiO₂ by 27.5 ± 3.1 kJ/mol. The metastability explains the rarity of the natural occurrence of stetindite and the difficulty of its synthesis. Applying the obtained enthalpy of formation of CeSiO₄ from this work, along with those previously reported for USiO₄ and ThSiO₄, we developed an empirical energetic relation for actinide orthosilicates. The predicted enthalpies of formation of AnSiO₄ are then determined with a discussion of future strategies for efficiently immobilizing Pu or minor actinides in the zircon structure.

中文翻译：

---

CeSiO4的热力学：对Act系元素原硅酸盐的影响。

锆石（ZrSiO ₄，I 4 ₁ / amd）可以容纳act系元素，例如or ，铀和p。对于其他other系元素（例如p和n）的几种末端成员组成，已经确定了锆石结构。然而，由于合成这些材料和处理handling铀act系元素的困难，这些act系元素锆石结构类型的热力学性质在很大程度上是未知的。因此，我们已经完成了铈正硅酸stetindite（CeSiO的热力学研究₄），PuSiO的替代₄。首次形成CeSiO ₄的标准焓通过高温氧化物熔融溶液量热法得到的-C为-1971.9±3.6kJ / mol。菱铁矿相对于CeO ₂和SiO ₂能级为27.5±3.1 kJ / mol。亚稳性解释了斯氏体天然存在的罕见性及其合成的难度。应用从这项工作中获得的形成CeSiO _4的焓，以及先前报道的USiO ₄和ThSiO _4的焓，我们开发了act系元素原硅酸盐的经验能量关系。然后，通过对将来有效地将Pu或次4系元素固定在锆石结构中的策略的讨论中，确定AnSiO ₄形成的预计焓。