Structural Relaxation Dynamics and Annealing Effects of Sodium Silicate Glass

Abstract

Here we report high-precision measurements of structural relaxation dynamics in the glass transition range at the intermediate and short length scale for a strong sodium silicate glass during long annealing times. We evidence for the first time the heterogeneous dynamics at the intermediate range order by probing the acoustic longitudinal frequency in the GHz region by Brillouin light scattering spectroscopy. Or, from in-situ Raman measurements, we show that relaxation is indeed homogeneous at the interatomic length scale. Our results show that the dynamics at the intermediate range order contains two distinct relaxation time scales, a fast and a slow component, differing by about a 10-fold factor below Tg and approaching to one another past the glass transition. The slow relaxation time agrees with the shear relaxation time, proving that Si-O bond breaking constitutes the primary control of structural relaxation at the intermediate range order.

Revealing the fast atomic motion of network glasses

“…Similar behaviour of the density fluctuations has been also reported in molecular dynamic simulations 39,40 and dielectric spectroscopy studies of polymeric glasses 41 . Differently from previous studies and from macroscopic measurements [4][5][6][7]15,29,[32][33][34][35] , we do not find any evidence of physical aging on our experimental time scale of about B4-6 h at any T, not even close to T g . While the absence of physical aging at very low temperatures has been already reported for polymeric glasses 42 , the observed stationary dynamics in the glass transition region is completely unexpected.…”

“…We show that contrary to the common idea of an almost arrested dynamics, structural glasses are able to relax and rearrange their structure on a length scale of a few Angstroms. On cooling the system in the glassy state, the structural relaxation time strongly departs from the supercooled liquid behaviour and displays a weak temperature dependence, with the absence of any detectable aging not even in the glass transition region, in disagreement with macroscopic studies and theoretical approaches [4][5][6][7]15,29,[32][33][34][35] . The relaxation time is found to be surprisingly fast, B100-1,000 s, even hundreds of degrees below T g , in contrasts with the general idea of an ultraslow dynamics in the deep glassy state.…”

“…Among prototypical network glasses, sodium silicates are intensively studied mainly due to their central role in geoscience and glass technology [25][26][27][28][29] . On increasing the sodium concentration, the three-dimensional network of SiO 4 tetrahedra is progressively 'depolymerized' by the appearance of non-bridging oxygens compensating the nearby incorporated sodium ions 25 .…”

Chemically stabilized δ-Bi2O3 phase: Raman scattering and X-ray diffraction studies

“…This method guarantees reproducible spectra with low uncertainty on the Raman intensities and assume that fluorescence is mostly originated from electronic transition 28 . Second, Raman spectra were normalized to the band at 635 cm -1 (Fig.…”

Joint Raman spectroscopic and quantum chemical analysis of the vibrational features of Cs2RuO4

“…Moreover, small variations are much easier to visualize, as they are too small to appear unambiguously on the simple comparison of two spectra, because of insufficient signal‐to‐noise ratio. This method has been applied in similar Raman studies on different materials where the spectral changes are not obvious . Upon increasing the laser power in the 2–36 mW power range, the Raman spectra remain qualitatively the same.…”