Based on a few assumptions regarding crystal construction, the structural, elastic anisotropic and thermophysical properties of advanced U–Si system and baseline UO₂ have been investigated through a first-principles density functional theory (DFT) method. The calculated lattice constants are in good agreement with the previous experimental and theoretical values. The elastic properties, including bulk modulus, shear modulus, Young’s modulus, Pugh’s B/G ratio, Poisson’s ratio and elastic anisotropy are derived from the elastic data \({C}_{ij}\). The calculation results show that the U₃Si₂ and β-U₃Si materials are brittle, while single-crystal UO₂ is ductile. Based on Poisson’s ratio, the advanced U–Si compounds and the baseline UO₂ compound will have the different elastic deformations. Moreover, the U₃Si₂ and β-U₃Si have elastic anisotropy behavior, while the UO₂ with an elastic isotropic characteristic mainly. Finally, Debye temperature, melting point, Voight harness and the hoop stress are predicted through different empirical formulas. The hoop stress of UO₂ is larger than that for U₃Si₂ and β-U₃Si. There will be highlight implications of these calculated data for future U–Si fuel pellets’ design and preparation.

Graphical abstract

中文翻译：

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先进的 U-Si 燃料与基线 UO2 的结构、弹性各向异性和热物理性质的可比性：DTF 方法

基于一些关于晶体结构的假设，通过第一性原理密度泛函理论 (DFT) 方法研究了先进 U-Si 系统和基线 UO _{2的结构、弹性各向异性和热物理性质。}计算的晶格常数与之前的实验值和理论值非常吻合。弹性特性，包括体积模量、剪切模量、杨氏模量、Pugh 的B / G比、泊松比和弹性各向异性是从弹性数据\({C}_{ij}\)推导出来的。计算结果表明，U ₃ Si ₂和β-U ₃ Si 材料较脆，而单晶UO₂是延展性的。基于泊松比，高级U-Si 化合物和基线UO ₂化合物将具有不同的弹性变形。此外，U ₃ Si ₂和β-U ₃ Si 具有弹性各向异性特性，而UO ₂主要具有弹性各向同性特性。最后，通过不同的经验公式预测德拜温度、熔点、沃特线束和环向应力。UO ₂的环向应力大于U ₃ Si ₂和β-U ₃ Si 的环向应力。这些计算数据将对未来 U-Si 燃料芯块的设计和制备产生重要影响。

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