Using Partial Differential Equations to Model the Moving Front in Heated Ultrastable Glasses
0Day 2 | 4:30 PM–5:00 PM
"Using Partial Differential Equations to Model the Moving Front in Heated Ultrastable Glasses"
Presented by:
Koksal Karakus, Central Michigan University, Mount Pleasant MI USA
https://qubeshub.org/community/groups/simiode/expo/2025
Abstract: Heating a conventional glass above its glass transition temperature significantly reduces its relaxation time as the material loses its rigidity. This transition may not occur uniformly due to thermal gradients and local structural variations, leading to spatial differences in relaxation behavior. However, for ultrastable glasses, which are prepared by vapor deposition, this change starts at the free surface and a front of mobility propagates towards the interior with a constant velocity. This velocity seems to depend on the thermal stability of the glass as well as the annealing temperature. We attempt to describe this phenomenon as a solution to a nonlinear partial differential equation that minimizes the free energy functional of the system. We start with an Allen-Cahn equation that has an exact traveling wave solution, from which we derive a potential function as outlined in the SL-TS2 model.