Hermansen Christian, Rodrigues Bruno P, Wondraczek Lothar, Yue Yuanzheng
Section of Chemistry, Aalborg University, 9220 Aalborg, Denmark.
Otto Schott Institute of Materials Research, University of Jena, 07743 Jena, Germany.
J Chem Phys. 2014 Dec 28;141(24):244502. doi: 10.1063/1.4904287.
We present a topological model for binary phosphate glasses that builds on the previously introduced concepts of the modifying ion sub-network and the strength of modifier constraints. The validity of the model is confirmed by the correct prediction of Tg(x) for covalent polyphosphoric acids where the model reduces to classical constraint counting. The constraints on the modifying cations are linear constraints to first neighbor non-bridging oxygens, and all angular constraints are broken as expected for ionic bonding. For small modifying cations, such as Li(+), the linear constraints are almost fully intact, but for larger ions, a significant fraction is broken. By accounting for the fraction of intact modifying ion related constraints, qγ, the Tg(x) of alkali phosphate glasses is predicted. By examining alkali, alkaline earth, and rare earth metaphosphate glasses, we find that the effective number of intact constraints per modifying cation is linearly related to the charge-to-distance ratio of the modifying cation to oxygen.
我们提出了一种用于二元磷酸盐玻璃的拓扑模型，该模型基于先前引入的改性离子子网概念和改性剂约束强度。对于共价多磷酸，该模型简化为经典的约束计数，通过对Tg(x)的正确预测证实了该模型的有效性。对改性阳离子的约束是对第一近邻非桥氧的线性约束，并且所有角度约束如离子键所预期的那样被打破。对于小的改性阳离子，如Li(+)，线性约束几乎完全完整，但对于较大的离子，很大一部分被打破。通过考虑与改性离子相关的完整约束分数qγ，预测了碱金属磷酸盐玻璃的Tg(x)。通过研究碱金属、碱土金属和稀土偏磷酸盐玻璃，我们发现每个改性阳离子的有效完整约束数与改性阳离子与氧的电荷-距离比呈线性关系。
