The nature of the amorphous state has been notably difficult to ascertain at the microscopic level. In addition to the fundamental importance of understanding the amorphous state, potential changes to amorphous structures as a result of radiation damage have direct implications for the pressing problem of nuclear waste encapsulation. Here, we develop new methods to identify and quantify the damage produced by high-energy collision cascades that are applicable to amorphous structures and perform large-scale molecular dynamics simulations of high-energy collision cascades in a model zircon system. We find that, whereas the averaged probes of order such as pair distribution function do not indicate structural changes, local coordination analysis shows that the amorphous structure substantially evolves due to radiation damage. Our analysis shows a correlation between the local structural changes and enthalpy. Important implications for the long-term storage of nuclear waste follow from our detection of significant local density inhomogeneities. Although we do not reach the point of convergence where the changes of the amorphous structure saturate, our results imply that the nature of this new converged amorphous state will be of substantial interest in future experimental and modelling work.

中文翻译：

---

辐照下非晶结构的演变：锆石案例研究

非晶态的性质在微观水平上特别难以确定。除了了解无定形状态的基本重要性之外，辐射损伤导致的无定形结构的潜在变化对核废料封装的紧迫问题也有直接影响。在这里，我们开发了新方法来识别和量化适用于非晶结构的高能碰撞级联产生的损伤，并对模型锆石系统中的高能碰撞级联进行大规模分子动力学模拟。我们发现，虽然对分布函数等有序的平均探针并不能表明结构变化，但局部协调分析表明，由于辐射损伤，非晶结构发生了实质性的变化。我们的分析显示了局部结构变化与焓之间的相关性。我们检测到显着的局部密度不均匀性对核废料的长期储存具有重要意义。尽管我们没有达到非晶结构变化饱和的收敛点，但我们的结果表明，这种新的收敛非晶态的性质将在未来的实验和建模工作中产生重大意义。