分子动力学模拟钠硼硅酸盐玻璃电子辐照诱导的结构演化效应

发布时间：2018-03-06 08:20

本文选题：硼硅酸盐玻璃　切入点：分子动力学　出处：《物理学报》2017年10期 　论文类型：期刊论文

【摘要】：钠硼硅酸盐玻璃作为高放射废物玻璃固化体的候选材料之一,已有大量实验对该类玻璃开展了电子或重离子的辐照效应研究.然而,在理论计算与模拟方面的工作却很少,目前主要集中于重离子的辐照效应,对电子的辐照效应的模拟尚未见报道.本文利用分子动力学工具提出一种新的方法,以实现对电子辐照诱导的玻璃结构演化进行模拟.该方法基于实验中玻璃的结构变化特点,即实验中的拉曼结果已经证实:在大剂量的电子辐照后的玻璃中存在分子氧的事实,由于这些分子氧不会与其他粒子发生相互作用,因而可以通过从体系中逐步地移除一定数量氧原子的方式,以达到模拟大剂量电子辐照的情形,进而得到电子辐照后的玻璃的结构信息.模拟结果显示:随着移除氧原子的数量增加,玻璃中的Si—O—Si平均键角逐渐减小;而且玻璃中的小环数量会因氧的逐渐减少而逐渐增加;玻璃中部分[BO4]结构会转变为[BO3]结构,最终这种转变会达到饱和;大量移除氧之后,玻璃中的钠元素也出现明显的相分离.这些模拟辐照的玻璃结构特性能较好地与实验中的硼硅酸盐玻璃电子辐照诱导的结构变化符合.因此,本文提出的方法有望为通过分子动力学模拟硼硅酸盐玻璃的电子辐照效应提供新思路.
[Abstract]:Sodium borosilicate glass is one of the candidate materials for high radiation waste glass solidification. A large number of experiments have been carried out to study the effects of electron or heavy ion irradiation on this kind of glass. However, little work has been done in theoretical calculation and simulation. At present, it is mainly focused on the irradiation effect of heavy ions, but the simulation of electron irradiation effect has not been reported. In this paper, a new method is proposed by using molecular dynamics tools. In order to simulate the evolution of glass structure induced by electron irradiation, this method is based on the structural characteristics of glass in the experiment, that is, the Raman results in the experiment have proved that there is molecular oxygen in the glass irradiated by large doses of electrons. Because these molecular oxygen do not interact with other particles, it is possible to simulate large doses of electron irradiation by gradually removing a certain number of oxygen atoms from the system. The simulation results show that the average bond angle of Si-O-Si decreases with the increase of the number of oxygen atoms removed, and the number of small rings in the glass increases with the decrease of oxygen. Part of the [BO4] structure in the glass changes to the [BO3] structure, which eventually reaches saturation; after a lot of oxygen removal, The phase separation of sodium elements in glass is also obvious. The special properties of these simulated irradiated glasses are in good agreement with the structural changes induced by electron irradiation of borosilicate glasses in the experiment. The method proposed in this paper is expected to provide a new idea for simulating the electron irradiation effect of borosilicate glass by molecular dynamics.
【作者单位】：兰州大学核科学与技术学院;兰州大学特殊功能材料与结构设计教育部重点实验室;
【基金】：国家自然科学基金(批准号:11505085,11505084) 中央高校基本科研业务费专项资金(批准号:lzujbky-2015-68,lzujbky-2016-37)资助的课题~~
【分类号】：TQ171.1

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