The advent of high temperatures superconductors (HTS) will enable the development of compact fusion reactors capable of delivering large quantities of low carbon energy. However, the inside of a fusion reactor is a hostile environment and bombardment by high energy neutrons will alter the microstructure of constituent materials, including the HTS in the magnets. Key to understanding the evolution of a material’s microstructure when subjected to neutron irradiation is knowledge of the defect population in the starting material. Therefore, this work uses density functional theory (DFT) simulations, combined with simple thermodynamics, to create a point defect model that enables prediction of the types and concentrations of defects present in a model HTS, YBa₂Cu₃O₇, under a range of fabrication conditions. The simulations predict that the defect chemistry of YBa₂Cu₃O₇ is dominated by oxygen defects, predominantly vacancies, in agreement with prior experimental observations. Interestingly, the simulations predict that the exchange of Y and Ba atoms is the second lowest energy defect process in YBa₂Cu₃O₇ after the oxygen Frenkel process. Furthermore, the point defect model shows that any cation non-stoichiometry will also be accommodated via antiste defects rather than either vacancies or interstitials. Overall, these results suggest that future fusion magnets will contain a high concentration of oxygen and cation antisite defects and that these must be considered in future studies of the evolution of HTS materials under irradiation.

高温超导体（HTS）的出现将使紧凑型聚变反应堆的开发成为可能，该反应堆能够输送大量的低碳能量。但是，聚变反应堆内部是一个不利的环境，高能中子轰击将改变组成材料的微观结构，包括磁体中的高温超导。了解中子辐照时材料微观结构演变的关键是了解原材料中的缺陷数量。因此，这项工作使用密度泛函理论（DFT）模拟，并结合简单的热力学，创建了一个点缺陷模型，该模型可以预测HTS，YBa ₂ Cu ₃ O ₇模型中存在的缺陷的类型和浓度。，在一定的制造条件下。该模拟预测，与先前的实验观察结果一致，YBa ₂ Cu ₃ O ₇的缺陷化学主要由氧缺陷（主要是空位）决定。有趣的是，模拟预测Y和Ba原子的交换是YBa ₂ Cu ₃ O _7中第二低的能量缺陷过程。氧气弗伦克尔工艺之后。此外，点缺陷模型显示，任何阳离子的非化学计量也将通过反ste缺陷而不是空位或间隙来适应。总体而言，这些结果表明，未来的聚变磁体将包含高浓度的氧和阳离子反位缺陷，并且在未来对HTS材料在辐射下的演化的研究中必须考虑这些缺陷。