Aging to equilibrium dynamics of SiO2

Area of Science:

• Materials Science
• Computational Physics
• Chemical Engineering

Background:

• Aging dynamics in amorphous materials like SiO2 are crucial for understanding their long-term stability and properties.
• Previous studies often focused on equilibrium states or short aging times, limiting insights into the transition dynamics.

Purpose of the Study:

• To investigate the aging dynamics of amorphous SiO2 using molecular dynamics simulations.
• To characterize the transition from out-of-equilibrium to equilibrium states after temperature quenching.
• To analyze the behavior of partial structure factors, intermediate scattering function, and mean-square displacement during aging.

Main Methods:

• Utilizing molecular dynamics computer simulations with the BKS model for SiO2.
• Performing simulations starting from equilibrated configurations at high temperatures and quenching to lower temperatures.
• Analyzing the generalized incoherent intermediate scattering function (Cq) and mean-square displacement (Δr2) over various waiting times (tw).

Main Results:

• Three distinct aging regimes were identified based on waiting time (tw).
• Short tw: Fast decay without plateau in Cq and Δr2. Intermediate tw: Plateau formation, time superposition, and scaling behavior.
• Long tw: System reaches equilibrium, independent of initial temperature (Ti) and tw.

Conclusions:

• The study successfully characterized the out-of-equilibrium to equilibrium transition in SiO2 aging dynamics.
• Observed time superposition and scaling behaviors provide a framework for understanding amorphous material aging.
• The findings offer valuable insights for predicting the long-term performance of silica-based materials.