Department of Materials, Imperial College London, London SW7 2AZ, UK.
Phys Chem Chem Phys. 2018 Jul 4;20(26):17624-17636. doi: 10.1039/c8cp00675j.
In this work interfaces between (Na2O)x(SiO2)1-x glasses (for x = 0.0, 0.1 and 0.2) and TiO2 crystals are simulated using molecular dynamics and empirical potentials. Interfaces are presented for the distinct terminating surfaces of TiO2 with Miller indices ≤2, the properties of which have been investigated using atomistic models. Simulations showed that partially ordered layers had been induced in the glass close to the interfaces, with successive oxygen-rich and cation-rich planes being noted. The first silicate layer in contact with the crystal tended to be highly-structured, with Si ions occupying well-defined positions that depend on the orientation of the crystal at the interface, and showing 2-dimensional ordering depending on glass composition. Finally, interface energies were calculated. These indicated that the interface formation may stabilise a crystal surface in comparison to maintaining a free surface. Results are presented suggesting that the structural flexibility of the glass network allows it to conform to the crystal, thereby providing charge compensation and avoiding large relaxation of the crystal structure close to the interfaces. Such interfacial properties could be crucial to improving phenomenological models of glass-crystal composite properties.
本文使用分子动力学和经验势模拟了（Na2O）x（SiO2）1-x 玻璃（x = 0.0、0.1 和 0.2）与 TiO2 晶体之间的界面。介绍了具有 ≤2 Miller 指数的 TiO2 不同终止表面的界面，使用原子模型研究了这些界面的性质。模拟表明，在靠近界面的玻璃中诱导了部分有序层，其中注意到富氧和富阳离子层依次出现。与晶体接触的第一个硅酸盐层倾向于高度结构化，Si 离子占据取决于界面处晶体取向的明确定位，并根据玻璃组成显示二维有序。最后，计算了界面能。这些表明与保持自由表面相比，界面形成可能稳定晶体表面。结果表明，玻璃网络的结构灵活性允许其适应晶体，从而提供电荷补偿并避免晶体结构在界面附近的大松弛。这种界面性质对于改进玻璃-晶体复合材料性质的唯象模型可能至关重要。
