Mechanical properties of glasses and TiO2 nanocrystal glass composites in BaO–TiO2–B2O3 system

• Young's modulus and Poisson's ratio of glasses were calculated.
• Results correlated to the fraction of BO4 and BO3 structural units.
• Mechanical properties improved upon nanocrystallization of the glasses.
• Fracture toughness of glass-nanocrystal composites was dependent on surface features.

Glasses and glass-nanocrystal (anatase TiO2) composites in BaO–TiO2–B2O3 system were fabricated by conventional melt-quenching technique and controlled heat treatment respectively. Poisson's ratio and Young's moduli were predicted through Makishima–Mackenzie theoretical equation for the as-quenched glasses by taking the four and three coordinated borons into account. Mechanical properties of the glasses and glass-nanocrystal composites were investigated in detail through nanoindentation and microindentation studies. Predicted Young's moduli of glasses were found to be in reasonable agreement with nanoindentation measurements. Hardness and Young's modulus were enhanced with increasing volume fraction of nanocrystallites of TiO2 in glass matrix whereas fracture toughness was found susceptible to the surface features. The results were correlated to the structural units and nanocrystals present in the glasses.