Revealing Structural Relaxation of Optical Glass Through the Temperature Dependence of Young's Modulus

Structural relaxation is one of the most important features of a glass material at an elevated temperature. This study aims to obtain an insight into the structural relaxation process of a typical optical glass. Experimentally, a high‐temperature impulse excitation technique was used to explore the mechanism through monitoring the variation of the Young's modulus of the material. Theoretically, the Tool–Narayanaswamy–Moynihan ( TNM ) model was employed to describe the variation of modulus with time and temperature. It was found that the parameterized TNM model obtained by modulus data could be used to achieve a more subtle description of the variation of coefficient of thermal expansion during structural relaxation, which is vital for thermoforming a glass product.