Improving the mechanical properties of a sodium borosilicate glass through spinodal decomposition

The brittleness of oxide glasses remains a critical problem, limiting their suitability for high-performance and safety-critical applications. In this study, we attempt to address this by synthesizing nanostructures in sodium borosilicate glasses through phase separation. While most previous work on the mechanical properties of phase-separated glasses has focused on phase separation through nucleation and growth, we here create interconnected structures through spinodal decomposition. Interestingly, this leads to improvements in Vickers hardness (from 5.8 to 6.2 GPa), crack initiation resistance (from 4.9 to 8.1 N), and fracture toughness (from 0.85 to 1.09 MPa⋅m^1/2). We show that the interconnected glassy phases deflect the propagating cracks, causing the required energy for cracks to cross phase boundaries to increase when subjected to external stress. This study deepens the understanding of how to address the brittleness problem of oxide glasses and provides a promising way to design high-performance glass materials.