## 3 Results
Computed main coordination number distribution of the number of non-bonding and bonding oxygen atoms is based on their boron concentration. **(b)** Effect of boron substitution on the coordination number for MD simulation of glass compositions 6P55-0B to 6P55-15B at 300 K. Please note that the coordination numbers 1, 2, 5 and 6 are identical and perfectly aligned, appearing as a single curve when overlaid under 6 (yellow). **(c)** Plot of oxygen packing density as a function of B\({}_{2}\)O\({}_{3}\) substitution from both computational and experimental outcomes. **(d)** Plot showing the variation of molar volume, \(V_{m}\), with B\({}_{2}\)O\({}_{3}\) substitution throughout the glass composition series. Figure 6: Effect of boron substitution on the \(Q^{n}\) species of **(a)** boron ions and **(b)** silicon ions for MD-simulated glass composition series 6P55-0B to 6P55-15B at 300 K. Please note that Q\({}^{5}\) and Q\({}^{6}\) are identical and perfectly aligned, appearing as a single curve when overlaid. increasing boron substitution contributes to the formation of NBOs, which alters the network structure. \(Q^{2}\) peaks at 40.414 for 6P55-10B, suggesting optimal connectivity within the network at this composition. The slight decrease in 6P55-15B indicates some disruption in bridging due to increased boron content. \(Q^{3}\) values vary, indicating changes in the connectivity of the network. The decline in \(Q^{3}\) from 6P55-5B to 6P55-15B may suggest a less stable network as boron content increases. \(Q^{4}\) is highest in 6P55-5B and decreases significantly in higher boron compositions. This trend suggests that while some connectivity is retained, the overall polymerization degree may reduce with excess boron, affecting the network's integrity. The transition from a silica-dominated network to one that incorporates boron leads to the formation of non-bridging oxygens and a complex balance between connectivity and stability. Therefore, the results suggest that a moderate level of boron (as seen in 6P55-10B) provides the best balance of bridging connections and structural integrity, while higher boron levels may disrupt this balance. The percent connectivity trend of various bonds (Si-O-Si, B-O-B, and Si-O-B) within the glass network, obtained through MD simulations at 300 K, as displayed in Figure 7, provides valuable insights into the structural evolution of the material as boron substitutes silica. In the glass network, silicon and boron atoms are connected by oxygen bridges to form tetrahedral units. Percent connectivity refers to the proportion of bonds formed between neighboring atoms in the network relative to the maximum number of possible bonds. This connectivity measure reflects how interconnected the atomic structure is. As boron replaces silicon in the glass structure per the composition series, the connectivity trends of the different bonds change. Specifically, the formation of Si-O-Si bonds decreases, while B-O-B and Si-O-B bonds increase. These changes in connectivity play a crucial part in understanding the structural effects of boron substitution, as they influence network integrity, \(T_{g}\), density, and sintering behavior. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Glass** & \(Q^{1}\) & \(Q^{2}\) & \(Q^{3}\) & \(Q^{4}\) \\ \hline
6P55-0B & 0.000 & 0.000 & 0.000 & 0.000 \\
6P55-5B & 9.716 & 23.528 & 30.452 & 35.430 \\
6P55-10B & 16.819 & 40.414 & 25.358 & 14.992 \\
6P55-15B & 15.926 & 39.671 & 27.964 & 14.990 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: \(Q^{n}\) distribution of boron in glass composition network. Figure 7: The percent connectivity trend of the Si-O-Si, B-O-B, and Si-O-B bonds within the glass tetrahedra due to the increased boron substitution (mol%) obtained from MD computational simulation at 300 K.  
By analyzing these percent connectivity trends, we gain a deeper understanding of the structural, thermal, and mechanical implications of the boron substitution in the glass series.