Molecular dynamics modelling of the structure of barium silicate glasses BaO–SiO<sub>2</sub>

The addition of barium to silicate glasses is of interest for applications such as radiation or thermal shielding. The barium silicate system, xBaO–(100−x)SiO2, has a glass forming region around x=25–40. Phase separation occurs at the lower range of x and has been a focus of previous studies. However, there have been very few structural studies of barium silicate glasses using diffraction or modelling. Here new results are presented from molecular dynamics modelling of glasses with x=25, 33.3, 40 and 50. The glass models have the expected silicate network and the short range order around Ba typically has BaO peak distance of 2.79Å and coordination of approximately 7, which is not similar to the crystals with x≤40. The x=40 glass model does not show any evidence of layered structures with approximately 4.2Å spacing which were previously hypothesised.

在硅酸盐玻璃中添加钡对于诸如辐射屏蔽或热屏蔽等应用具有重要意义。硅酸钡体系，即xBaO - (100 - x)SiO₂，在x = 25 - 40左右有一个玻璃形成区域。在x的较低取值范围会发生相分离，这是先前研究的重点。然而，利用衍射或建模对硅酸钡玻璃进行的结构研究却很少。这里给出了对x = 25、33.3、40和50的玻璃进行分子动力学建模的新结果。玻璃模型具有预期的硅酸盐网络，Ba周围的短程有序结构中，BaO峰间距通常为2.79Å，配位数约为7，这与x≤40的晶体不同。x = 40的玻璃模型没有显示出任何先前假设的、间距约为4.2Å的层状结构的迹象。