Effect of fictive temperature on surface structural chemistry of soda-lime-silica glass

Title data

Roy, Barsheek ; Rosin, Andreas ; Gerdes, Thorsten ; Schafföner, Stefan:
Effect of fictive temperature on surface structural chemistry of soda-lime-silica glass.
2022
Event: 26th International Congress on Glass , 3-8 July, 2022 , Berlin, Germany.
(Conference item: Conference , Lecture )

Project information

Abstract in another language

The fictive temperature (Tf) of soda-lime-silica (SLS) glass is marked by the frozen state of memory at the point of transition from the supercooled liquid state to the rigid solid state, that is retained at room temperature. A lower Tf is theoretically known to be associated with a denser network.

This study endeavoured to investigate the influence of fictive temperature on surface chemistry associated with the free volume of the silicate network; with consequent variation of hardness as a function of depth from the glass surface. The Tf of SLS glass (Tg: 559 ℃ to 575 ℃) was lowered from 570 ℃ to 510 ℃, by subjecting it to a prolonged heat-treatment of 36 hours at 510 ℃ to reach an equilibrium state. The shift in fictive temperature after the treatment was confirmed by specular reflectance infrared spectroscopy (SR-IR). The variation of silicate network connectivity was studied as a function of depth from SLS glass surfaces with two different fictive temperatures (510 ℃ and 570 ℃) up to a depth of about 110 nm – by X-ray photoelectron spectroscopic investigations. It was found that the concentration of the contribution of network modifier cations and surface hydrous species to non-bridging oxygen (NBO), represented by the atomic ratio of ((Ototal - OSi-O-Si) / Si) – decreased with lowering the fictive temperature of SLS glass. This is indicative of repolymerization of vicinal silanol groups, marked by the decrease of the concentration of surface hydrous species. The alteration of surface mechanical property was complementary to the evidence of stronger network connectivity in terms of a notable rise in Martens hardness with lower fictive temperature up to the same depth of 110 nm.

An SLS glass with lower Tf thus possessed stronger surface network connectivity with lower concentration of NBOs, accompanied by higher Martens hardness.