Investigating relaxation of glassy materials based on natural vibration of beam : a comparative study of borosilicate and chalcogenide glasses

Abstract

The present work investigates the validity of using the frequency and decay rate of free-free beam vibration, which are measured by the impulse excitation technique (IET), to characterize the viscoelastic properties of glass in the temperature range of glass transition. Based first on the classical Burgers model, we show that the temperature-dependent flow viscosity of borosilicate glass, calculated from the measured frequency and amplitude decay rate of the flexural vibration, agrees very well with the existing data. While for chalcogenide glass, the same calculation approach does not render the similar agreement, and the reason probably lies in non-exponential effects. To comprehend the IET data in the temperature range of glass transition, we propose a simplified theoretical framework for describing the transition from the solid-like to liquid-like viscoelastic behavior and discuss the cause of difference of the rheology behaviors of these two types of glass based on the formulation of non-exponential relaxation.