Size-dependent elasticity of amorphous silica nanowire: A molecular dynamics study

Size-dependent Young's modulus of amorphous silica nanowires was systematically studied using classical molecular dynamics simulations. Our study showed that different sample preparation methods (casting, cutting, and cutting-straining) can cause substantial difference in the elastic response of silica nanowires. An eigenstress model was developed to describe the size-dependent elasticity and proved to be applicable in silica nanowires with radius down to 2 nm. Coupling between the core softening and the surface stiffening dictates the overall elasticity of silica nanowires, whose structure is different from that of bulk silica glass mainly in the surface region where small membered rings and coordination defects reside.