Investigation of the Structures of Sodium Borophosphate Glasses by Reverse Monte Carlo Modeling to Examine the Origins of the Mixed Glass Former Effect
Investigation of the Structures of Sodium Borophosphate Glasses by Reverse Monte Carlo Modeling to Examine the Origins of the Mixed Glass Former Effect
复制标题
DOI：
10.1021/jp2085654
复制
发表时间：
2012-01-12
影响因子：
3.7
通讯作者：
Martin, Steve W.
中科院分区：
文献类型：
--
作者：
Schuch, Michael;Christensen, Randi;Martin, Steve W.
基于先前报道的x射线衍射（XRD）数据，我们提出了0.35Na(2)O + 0.65 [xB(2)O(3) + (1 x)P2O5]玻璃的反向蒙特卡罗模型的新结果。生成的结构模型能够准确再现XRD测定的对相关函数和结构因子，同时保持正电荷阳离子与带负电荷的磷酸、硼酸氧阴离子基团之间近乎完美的电荷中性，同时保持各原子对之间适当的键距。然而，这些模型不能成功地解释网络形成单元（nfu）的浓度，正如最近的理论模型和具有相似化学计量的硼酸钠玻璃的魔角旋转核磁共振（MAS NMR）数据所预测的那样。通过对模型的进一步改进，NFU浓度也可以成功地再现。对于优化的结构，我们研究了电导率活化能是否与RMC模型中确定的钠远程扩散路径的体积分数相关的问题。
We present new results for the Reverse Monte Carlo modeling of 0.35Na(2)O + 0.65 [xB(2)O(3) + (1 x)P2O5] glasses based on previously reported X-ray diffraction (XRD) data. Structural models have been generated that accurately reproduce the pair correlation functions and structure factors determined by XRD while maintaining nearly perfect charge neutrality between the positively charged cations and the negatively charged phosphate and borate oxyanion groups and while maintaining appropriate bond distances between the various atom pairs. These models, however, are not successful in accounting for the concentrations of network forming units (NFUs), as predicted by recent theoretical modeling and by magic-angle spinning nuclear magnetic resonance (MAS NMR) data for sodium borate glasses with similar stoichiometry. By a further refinement of the modeling, the NFU concentrations can be successfully reproduced as well. For the optimized structures, we investigate the question if the conductivity activation energy correlates with the volume fraction of the sodium long-range diffusion paths, as identified in the RMC modeling.