Fictive temperature and fictive pressure measurement of silica glasses using FTIR method: For thick samples and samples containing Si–H

A simple IR method using the silica structural band at ~ 2260 cm− 1 was previously developed to determine the fictive temperature of silica and high silica glasses. The method has been used to determine the fictive temperature of silica glasses with an unknown thermal history as well as for the study of their relaxation kinetics. In the present study, a similar technique using the silica structural band at ~ 2660 cm− 1 was explored. It was found that the use of the 2660 cm− 1 band is advantageous over the use of the 2260 cm− 1 band in some applications. One advantage is for silica glasses containing Si–H bonding, as Si–H gives absorbance close to the silica structural band at ~ 2260 cm− 1, but not at ~ 2660 cm− 1. The other advantage is that thicker samples can be used since the absorbance per unit thickness is less at ~ 2660 cm− 1. The use of a thicker sample can be advantageous because the influence of surface structural relaxation effects is reduced. It was also shown that the method of fictive temperature measurement can be extended to determine the fictive pressure of silica glasses treated under various high pressures at a constant temperature.