Understanding the physics of the disordered state: universality of phenomena in glasses and resistance to amorphization by radiation damage

非晶固体在技术应用中有着广泛的应用。眼镜是我们日常生活中非常熟悉的物品。然而，与拓扑有序的固体相比，它们在实验和理论上都知之甚少。在过去的几十年里，实验研究产生了许多新的数据，但对这些数据的理论理解仍然缺乏。通过将观察到的行为与其中的微观过程联系起来，这一建议将推进对非晶态物理学的基本理解。该方案由两部分组成，即普遍松弛现象的微观描述和抗辐射损伤非晶化的认识。在过去的三十年里，无定形固体因其普遍的弛豫特性而吸引了科学家，其中许多弛豫特性在晶体中是看不到的。本提案的第一部分旨在获得对非晶固体中普遍性现象起源的基本理解，这一问题长期困扰着科学家。我提出了一个普遍的问题，即与无序状态的本质相关的复杂性如何导致观察到的现象的简单性（普遍性）。在非晶固体中有几种主要的普遍性。在拟议的研究中，将解决以下问题：(a)玻璃和玻璃转变时的超冷液体中的拉伸指数弛豫；(b)刚性渗流点周围松弛的普适性；(c)低温热容和吸声的通用性。我将提供这些现象的微观描述。这里重要的一点是把这些看似不同的松弛现象联系起来，用普遍局部松弛事件的动力学来描述它们。这些事件是玻璃中的基本弛豫量子，它们驱动微观尺度上的普遍弛豫现象。粒子辐照是产生非晶固体的方法之一，本提案的第二部分旨在了解是什么使材料在辐射损伤下非晶化。我对这一领域的兴趣是由安全封装高放射性核废料和剩余钚的需要引起的。为什么有些材料在高能离子的作用下很容易非晶化，而另一些材料则具有极强的抗蚀性，即使在很高的辐射剂量下也不会显示出结晶度的损失？尽管经过了几十年的研究，但抗辐射损伤非晶化的问题尚未得到普遍解决。我将研究许多材料抗辐射损伤非晶化的共同起源，使用我最近提出的原子间相互作用的类型，共价和离子性，在这一过程中起着重要作用。此外，我将研究其他因素如何与抗非晶化有关。最后，我将寻求提供一种定量微观理论，将材料的微观参数与其抗非晶化联系起来。这将允许预测具有高抗非晶化的材料。

Amorphous solids are widely used in technological applications. Glasses are very familiar objects to us in our everyday life. However, compared with topologically ordered solids, they are much less understood both experimentally and theoretically. In the last several decades, experimental studies have produced much new data, but the theoretical understanding of this data is still lacking. This proposal will advance fundamental understanding of the physics of the amorphous state, by linking the observed behaviour to microscopic processes in them. The proposal consists of two parts, the microscopic description of universal relaxation phenomena and understanding resistance to amorphization by radiation damage.Over the last three decades, amorphous solids have been fascinating scientists by the universality of their relaxation properties, many of which are not seen in crystals. The first part of this proposal is aimed at obtaining fundamental understanding of the origin of universality of phenomena in amorphous solids, which has long puzzled scientists. I formulate a general question of how the complexity related to the nature of disordered state gives rise to the simplicity (universality) of the observed phenomena. There are several main universality classes in amorphous solids. In the proposed research, the following will be addressed: (a) stretched-exponential relaxation in glasses and supecooled liquids at glass transition; (b) universality of relaxation around the rigidity percolation point; and (c) low-temperature universality of heat capacity and sound absorbtion. I will provide the microscopic description of these phenomena. The important point here is to relate these seemingly different relaxation phenomena, by describing them in terms of the dynamics of universal local relaxation events. These events are the elementary relaxation quanta in glasses which drive the universal relaxationphenomena at the microscopic scale.Particle irradiation is one of the ways of producing amorphous solids, and the second part of this proposal is aimed at understanding what makes a material amorphizable by radiation damage. My interest in this area is stimulated by the need to safely encapsulate highly radioactive nuclear waste and surplus Pu. Why some materials are readily amorphized by heavy energetic ions, whereas others are extremely resistant and do not show any loss of crystallinity even at very high radiation doses? Despite decades of research, the problem of resistance to amorphization by radiation damage is not generally solved. I will investigate the common origin of resistance to amorphization by radiation damage in many materials, using my recent proposal that the type of interatomic interactions, covalency and ionicity, plays an important role in this process. In addition, I will investigate how other factors may be relevant for resistance to amorphization. Finally, I will seek to provide a quantitative microscopic theory that links the microscopic parameters of a material to its resistance to amorphization. This will allow to predict materials with high resistance to amorphization.