Temperature Dependence of Elastic Properties for Amorphous SiO₂ by Molecular Dynamics Simulation

Large-scale and long-time molecular-dynamics simulations are used to investigate the temperature dependences of elastic properties for amorphous SiO₂. The elastic moduli increase in a temperature range up to 1600 K and decrease thereafter. The anomalous behaviour in elasticity is explained by analysing the changes of atomic-scale structure with respect to increment of temperature. The mechanism originates predominantly from distortion of the SiO₄ tetrahedra network in low-temperature ranges. At an elevated temperature range, thermal-induced Si--O bond stretching dominates the process and leads to normal temperature dependence of elastic properties.