Section of Chemistry, Aalborg University, DK-9000 Aalborg, Denmark.
J Chem Phys. 2010 Oct 21;133(15):154509. doi: 10.1063/1.3497036.
The connection between bulk glass properties and network topology is now well established. However, there has been little attention paid to the impact of network topology on the surface properties of glass. In this work, we report the impact of the network topology on both the transport properties (such as cationic inward diffusion) and the mechanical properties (such as hardness) of borate glasses with modified surfaces. We choose soda lime borate systems as the object of this study because of their interesting topological features, e.g., boron anomaly. An inward diffusion mechanism is employed to modify the glass surface compositions and hence the surface topology. We show that accurate quantitative predictions of the hardness of the modified surfaces can be made using topological constraint theory with temperature-dependent constraints. Experimental results reveal that Ca(2+) diffusion is most intense in glasses with lowest BO(4) fraction, whereas Na(+) diffusion is only significant when nonbridging oxygens start to form. These phenomena are interpreted in terms of the atomic packing and the local electrostatic environments of the cations.
大块玻璃性质与网络拓扑之间的关系现已得到充分证实。然而，人们很少关注网络拓扑对玻璃表面性质的影响。在这项工作中，我们报告了网络拓扑对经过表面改性的硼酸盐玻璃的传输性质（如阳离子内扩散）和机械性质（如硬度）的影响。我们选择苏打石灰硼酸盐系统作为这项研究的对象，是因为它们具有有趣的拓扑特征，例如硼反常。采用内扩散机制来改变玻璃表面的组成，从而改变表面拓扑。我们表明，使用具有温度相关约束的拓扑约束理论可以对改性表面的硬度进行准确的定量预测。实验结果表明，在 BO（4）分数最低的玻璃中，Ca（2+）的扩散最为强烈，而只有当非桥氧开始形成时，Na（+）的扩散才变得显著。这些现象可以根据阳离子的原子堆积和局部静电环境来解释。
