Uranium silicides are currently under investigation as accident tolerant fuels for light water reactors because of its high uranium density and high thermal conductivity. Surface energy as an important material property is required for modeling of gas bubble behavior in nuclear fuels using mesoscale approaches, such as phase field and rate theory methods. However, there is no such information available for uranium silicides from either experiment or theory. To this end, we study the surface properties of two uranium silicide compounds U₃Si₂ and U₃Si using first-principles calculations. Of the low-index facets of tetragonal U₃Si₂ and U₃Si, we study a total of 13 surfaces up to a maximum Miller index of 3. From the calculated surface energies, the equilibrium single crystal shapes of U₃Si₂ and U₃Si are obtained using Wulff construction. The dominant surface orientation, surface area weighted surface energy and surface anisotropy are predicted. The obtained surface properties of U₃Si₂ and U₃Si can be used for an accurate description of the morphology of fission gas bubbles in uranium silicide fuels in the future.

铀硅化物由于其高铀密度和高导热性，目前正在作为轻水反应堆的耐事故燃料进行研究。使用中尺度方法（例如相场和速率理论方法）对核燃料中的气泡行为进行建模时，需要表面能作为重要的材料属性。但是，从实验或理论上都没有有关硅化铀的此类信息。为此，我们使用第一性原理计算研究了两种铀硅化物化合物U ₃ Si ₂和U ₃ Si的表面性质。U ₃ Si ₂和U ₃的四边形的低折射率面Si，我们总共研究了13个表面，最大米勒指数为3。根据计算得出的表面能，使用Wulff结构获得了U ₃ Si ₂和U ₃ Si的平衡单晶形状。预测了主要的表面取向，表面积加权的表面能和表面各向异性。所获得的U ₃ Si ₂和U ₃ Si的表面性质可用于准确描述未来硅化铀燃料中裂变气泡的形态。