Humans primarily interact with information
technology through glass
touch screens, and the world would indeed be unrecognizable without
glass. However, the low toughness of oxide glasses continues to be
their Achilles heel, limiting both future applications and the possibility
to make thinner, more environmentally friendly glasses. Here, we show
that with proper control of plasticity mechanisms, record-high values
of fracture toughness for transparent bulk oxide glasses can be achieved.
Through proper combination of gas-mediated permanent densification
and rational composition design, we increase the glasses’ propensity
for plastic deformation. Specifically, we demonstrate a fracture toughness
of an aluminoborate glass (1.4 MPa m0.5) that is twice
as high as that of commercial glasses for mobile devices. Atomistic
simulations reveal that the densification of the adaptive aluminoborate
network increases coordination number changes and bond swapping, ultimately
enhancing plasticity and toughness upon fracture. Our findings thus
provide general insights into the intrinsic toughening mechanisms
of oxide glasses.