A new potential for radiation studies of borosilicate glass

Abstract

Borosilicate glass containing 70 mol% SiO 2 and 30 mol% B 2 O 3 is investigated theoretically using fixed charge potentials. An existing potential parameterisation for borosilicate glass is found to give good agreement for the bond angle and bond length distributions compared to experimental values but the optimal density is 30% higher than experiment. Therefore the potential parameters are refitted to give an optimal density of 2.1 g/cm 3 , in line with experiment. To determine the optimal density, a series of random initial structures are quenched at a rate of 5×10 12 K/s using constant volume molecular dynamics. An average of 10 such quenches is carried out for each fixed volume. For each quenched structure, the bond angles, bond lengths, mechanical properties and melting points are determined. The new parameterisation is found to give the density, bond angles, bond lengths and Young's modulus comparable with experimental data, however, the melting points and Poisson's ratio are higher than the reported experimental values. The displacement energy thresholds are computed to be similar to those determined with the earlier parameterisation, which is lower than those for ionic crystalline materials.

Molecular dynamics simulation of ballistic effects in simplified nuclear waste glasses

“…Coulombic interactions were treated by the Ewald summation method [46]. Parametrizations of the Buckingham potentials proposed by Jolley et al [43], Stoch et al [44] and Deng et al [33] were selected from literature for comparison (the Table enumerating the pair potential parameters can be found in supporting information). Further, depending upon the accuracy of the simulation with respect to experiment, one potential was selected for the glass preparation and the radiation effect simulations.…”

“…Several other potentials have been derived to simulate borosilicate glasses [37][38][39][40][41][42] but their use has been limited due to either their complexity or their failure to simulate some compositions. Three Buckingham-based potentials, proposed by Jolley et al [43], Deng et al [33] or Stoch et al [44] were tested in this work. The results obtained with these different potentials have been compared to explain the potential selected for the DC simulations.…”

Borate melt structure: Temperature‐dependent B–O bond lengths and coordination numbers from high‐energy X‐ray diffraction

“…Scattering data such as those presented herein can and should be used for stringent testing of atomistic models. Indeed, several sets of interatomic pair potentials have recently been derived for the modeling of borate glasses, and these would benefit from comparison to measurements. Using both the solid amorphous and liquid state data has several benefits, including the ability to compare to models at equilibrium at high temperatures.…”

Macroscopic and microscopic radiation effects on glass materials

“…分子动力学(MD)方法是将分子简化为运动粒子，通过势函数表述各个粒子间的相互作用 力，基于牛顿运动方程，求得粒子的运动轨迹。MD 可用于建立玻璃结构模型，研究辐照后玻璃 位移损伤，和级联反应产生的弹道效应等 [92] 。 分子动力学方法有三个基本步骤 [93] ：建模、计算和分析。建模，确定玻璃的初始构型，每 个粒子的初始速度、相互作用力等；计算，求解各个积分步长下的运动轨迹；分析，用统计分析 方法对玻璃的结构、动力学、能量等信息进行分析。势函数是分子动力学中重要的参数，关系着 原子间作用力的精确与否。常见的势函数有，Lennard-Jones 势和 Morse 势。Lennard-Jones 势函数是一个简单的经验势，用来描述非极性原子间的相互作用能。Morse 势是分子或原子间 势能的简易解析模型，可用来描述共价键的振动。 例如，研究者采用齐格勒-比尔扎克-利特马克(Ziegler，Biersack 和 Littmark，简称 ZBL) 势和 BKS 势，模拟玻璃辐照损伤中的原子间碰撞或级联效应问题 [92,94] 。Jan 等 [95] 在模拟钠硼硅 F o r R e v i e w O n l y 中国科学: 物理学 力学 天文学 http://physcn.scichina.com 和钠铝硅酸盐玻璃中的弹道效应时，采用 BKS 势描述原子间相互作用，但是 BKS 势不能很好描 述原子在高能碰撞时的相互作用。Zhou 等 [96] 在研究中采用 ZBL 势和 BKS 势构建高温环境辐射 级联效应模型，涉及到原子间距变小时转换为 ZBL 势。ZBL 势和 BKS 势结合在其他学者 [97,98] 的研究中也有使用，以此可保证能量和力的连续性。此外，BKS 势中包含的 Buckingham 项可 用来描述短程排斥作用和长程吸引作用，在多组分玻璃的建模有较好的优势 [99] 。…”