Structural ordering of SiO₂ glass exhibiting different fictive temperatures

The physical and structural parameters of glass depend on its preparation conditions. Fictive temperature, Tf, is a standard for glass obtained from the super-cooled liquid. Although the Tf value is discussed from the viewpoint of structural relaxation defined by infrared vibration, there should be structural correlations at the longer ranges, which are worthy of exploration. Here, we demonstrate the structural change of the intermediate range in SiO2 glasses with different Tf values using X-ray and neutron diffraction, inelastic light scattering, and positron annihilation spectroscopy. By annealing the SiO2 glasses, i.e., decreasing Tf, an increase in the first sharp diffraction peak (FSDP) heights and narrowing of the peak width are observed. Differential structure factor ΔS(Q) of neutron diffraction reveals a formation of the thermally derived O–O inter-tetrahedral correlation in high-Tf glass. Spectroscopic analyses (Raman scattering, stimulated Brillouin scattering, and positron annihilation spectroscopy) suggest that a certain structural change has occurred in the SiO2 glass exhibiting higher Tf values, confirming that these approaches can be used as probes for structural ordering. Considering ΔS(Q) of neutron diffraction, it is suggested that the structural changes in SiO2 glass with higher Tf values observed by spectroscopy correlate with oxygen-related structural change in the intermediate range. Since the observed structures of each analysis are different, these multiscale and quantitative examinations are important for precise examination of various random materials.