Effect of fictive temperature on medium range order in v-SiO2

The first-order Raman spectra of vitreous SiO2 between 10 and 650 cm(-1) have been measured as a function of sample fictive temperature, T-F, achieved by laser quenching. The changes observed in the high frequency range of the spectra, > 100 cm(-1), which is related to the short range order, are correlated with the shift of the 'Boson peak' (BP) which is present in the low frequency range, < 100 cm(-1), and characteristic of the medium-range order. Based on the non-continuous glassy structure model, these observations are attributed to a decrease in the size of domains, associated with a modification of the Si-O-Si angle distribution, with the increase of T-F. (C) 1997 Elsevier Science B.V.