Cover Photograph: Representative arrangements of 2‐ (L) and 3‐rings (R), in the near‐surface (top 12 Å) region for a 60SiO2.20Al2O3.20CaO (60:20:20) glass, from molecular dynamics simulations. There is little obvious sign of clustering of the rings, that is the distribution is largely homogeneous. Most 2‐rings are Al‐Al; no Si‐Si edge‐shared tetrahedra are seen, though there are a few Si‐Al 2‐rings. The simulations reveal higher concentrations of both 2‐ and 3‐rings in the surface, compared to the bulk, structure, for all compositions studied. In 60:20:20 composition, however, a maximum in 2‐ring and a minimum in 3‐ring surface relative enrichment were found. These extrema coincide with an observed maximum in electronegative contact charging behavior at this composition, as a function of silica content [https://doi.org/10.1111/ijag.15794].

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封面照片：通过分子动力学模拟，在60SiO2.22Al2O3.20CaO（60:20:20）玻璃的近表面（顶部12Å）区域中2个（L）和3个环（R）的代表性布置。环几乎没有聚集的迹象，即分布在很大程度上是均匀的。大多数2环是Al-Al。尽管有少量的Si-Al 2环，但没有看到Si-Si边缘共享的四面体。模拟显示，与所研究的所有成分的体积，结构相比，表面的2和3环浓度更高。但是，在60:20:20的组成中，发现2环最大，而3环表面相对富集最小。这些极值与该组成下所观察到的最大负电接触行为一致，这是二氧化硅含量的函数[https://doi.org/10.1111/ijag.15794]。