Relationship between the first sharp diffraction peak and physical properties of silicon dioxide (SiO2) glasses possessing different fictive temperatures

Investigating the correlation between glass structure and physical properties is important for development of novel functional materials. It is well known that the physical and structural parameters of glass depend on the preparation condition. Fictive temperature, T-f, is one of the standards of glass obtained from the super-cooled liquid state. Since the T-f value is defined using structural relaxation of overtone mode of Si-O-Si vibration, correlation of the T-f with the structural ordering at longer range is worthy for exploring. Here, we examine structural change of SiO2 glass possessing different T-f values probed by the first sharp diffraction peak (FSDP) observed in X-ray diffraction data. By annealing of SiO2 glass, i.e. decreasing of T-f, a sharpening of the FSDP is observed. Both structural periodicity and the correlation length of the FSDP decrease with increasing the T-f. It is suggested that increase of smaller structural units contributing to the FSDP is the origin of the increase of elastic modulus of SiO2 glasses. (C) 2020 The Ceramic Society of Japan. All rights reserved.