## 1 Introduction
In previous studies, [PERSON] et al. developed and investigated glass compositions within the SiO\({}_{2}\)-Na\({}_{2}\)O-K\({}_{2}\)O-CaO-MgO-P\({}_{2}\)O\({}_{5}\) system to optimize coatings for titanium-based and cobalt-chromium alloys [10]. Their research highlighted the 6P55 glass composition as a promising candidate due to its favorable thermal properties and biocompatibility. Specifically, the 6P55 composition was identified for its coefficient of thermal expansion (CTE) of 11 \(\times\) 10\({}^{-6}\)/\({}^{\circ}\)C, which closely matches the CTE of Ti6 Al4V at 9.8 \(\times\) 10\({}^{-6}\)/\({}^{\circ}\)C. This small difference (less than 4 \(\times\) 10\({}^{-6}\)/\({}^{\circ}\)C) minimizes thermal stresses and reduces the likelihood of cracking at the glass-metal interface during sintering [13; 14]. Additionally, compositions with silica content above 57 wt% exhibited reduced bioactivity, while those with silica content of 55 wt% or below showed optimal performance. These findings made 6P55 an ideal benchmark for further exploration. Building upon these findings, our study investigates the substitution of boron oxide for silica in the 6P55 glass composition to further enhance its properties. Borosilicate glasses, renowned for their lower transition temperatures, thermal shock resistance, and structural adaptability, offer promising opportunities for such modifications [15]. We systematically studied the structural changes in boron-substituted 6P55 glass by investigating four glasses with boron contents ranging from 0 to 15 wt% in 5 wt% increments. The substitution of boron oxide introduces non-bridging oxygens (NBOs), which disrupt the silica network, enhancing the glass's structural flexibility and adaptability. Boron, acting as a network former, transitions between three- and four-coordinate states depending on the presence of modifiers that serve as local charge compensators. These structural changes influence critical properties, including density, glass transition temperature (\(T_{\mathrm{g}}\)), and thermal expansion. To comprehensively understand these effects, our structural and compositional analysis examines key parameters, such as \(Q^{\mathrm{n}}\) distribution in silica and boron networks, oxygen speciation (bridging oxygen, non-bridging oxygen, and oxygen packing density), and their correlation to the glass's thermal and mechanical properties such as density and coefficient of thermal expansion (CTE). Molecular dynamics (MD) simulations and experimental results reveal that boron substitution optimizes the thermal and mechanical properties of the glass while maintaining bioactivity. The reduced \(T_{\mathrm{g}}\) and enhanced CTE alignment with Ti6 Al4V improve the adhesion and durability of the coating. Importantly, boron substitution does not compromise bioactivity, enabling the formation of a hydroxyapatite layer, crucial for osseointegration. This study also delves into the pivotal role of boron as a network former and its impact on overall glass structure and thermal behavior, highlighting its potential to optimize glass for biomedical applications. This comprehensive investigation of boron oxide substitution in 6P55 glass composition underscores its potential as an ideal coating for Ti6 Al4V implants. However, this work represents just one facet of an ongoing and broader study. Future investigations will focus on the biological performance of these compositions, evaluating their bioactivity, cell toxicity, and antimicrobial properties. This multifaceted approach aims to further our understanding of the interactions between implant materials and biological environments, ultimately advancing the field of implantable biomaterials and their clinical applications.