Journal of non-Crystalline Solids vol:316 issue:1 pages:138-145
This paper compares the microstructures of several glasses by measuring the Young's modulus and internal friction as a function of temperature, using the impulse excitation technique (IET). IET is based on the analysis of the resonant vibration of a solid material sample, induced by an impulse excitation. IET determines the mechanical resonant frequencies (f(x)) from which the elastic moduli can be calculated, and for each f(x) the corresponding internal friction (Q(-1)). It was found that the stiffness of quartz and borosilicate glasses increases with temperature. The stiffness of soda-lime and alumino-silicate glasses decreases with the increase of temperature. The change of stiffness of quartz and aluminosilicate glasses during heat-treatment is reversible, but that of borosilicate and soda-lime glasses is not. Explanations for the irreversibility are suggested based on the Q (1)-features of the glasses. Diffusion of network modifier ions in the glass network holes is proposed to cause a non-reversible stiffness change, whereas localised anelastic relaxation of network modifier ions leads to a reversible stiffness change. (C) 2003 Elsevier Science B.V. All rights reserved.