Effect of heat treatment on the surface chemical structure of glass: Oxygen speciation from in situ XPS analysis

Abstract

Compositional changes in unleached and acid‐leached soda‐lime silicate surfaces were tracked with in‐vacuo heating and X‐ray Photoelectron Spectroscopy. Surface oxygen speciation was determined using a stoichiometry‐based algorithm via elemental composition, instead of the typical O 1s peak‐fitting approach. Accurate surface hydroxyl quantification is shown to require dehydration at temperatures near 200°C. On the unleached surface, no change in surface hydroxyl density (~2.5 OH/nm2) is observed in the temperature range of 200°C‐500°C after the initial dehydration. However, repolymerization in the network (non‐bridging oxygen→bridging oxygen) is observed due to volatilization of sodium. The acid‐leached surface undergoes sodium out‐diffusion from the bulk at sub‐Tg temperatures with laterally resolved inhomogeneity and shows a reduction in the concentration of hydroxyls from 4.5 OH/nm2 (200°C) to 3.2 OH/nm2 (500°C) accompanied by an increase in bridging oxygen. These results suggest that when [OH] > 2.5~3/nm2, vicinal OH undergo dehydroxylation with evolution of water, whereas when [OH] < 2.5/nm2, most OHs are non‐interacting and isolated (at temperatures below Tg). Furthermore, at temperatures exceeding 300°C, sodium has enough thermal energy to desorb in vacuum and diffuse from the bulk (depending on the abundance & local structure).

Spectroscopic ellipsometry study of thickness and porosity of the alteration layer formed on international simple glass surface in aqueous corrosion conditions

“…It should also be noted that this temperature is high enough to induce dehydroxylation reactions of adjacent hydroxyl groups. 37 As a result, the void volume fraction obtained from TGA measurement is higher than that in the current study. and the pore-size distributions were determined using both adsorption and desorption curves.…”

Effects of tempering and heat strengthening on hardness, indentation fracture resistance, and wear of soda lime float glass

“…The NBO/Si ratio decreases slightly after HS treatments, which may be due to sodium volatilization during the high‐temperature processing. Sodium volatilization has been found to occur at temperatures greater than 400°C . Since the HS process involves heating at temperatures much higher than 400°C, it can be expected that the surface is depleted of sodium due to volatilization.…”

“…A high‐resolution scan of the C 1s region was collected at a 29 eV pass energy. To accurately calculate the atomic concentration from XPS, the relative sensitivity factor (RSF) values for all glass elements were obtained following the method described in previous publications . The relative atomic concentrations obtained from XPS spectra were corrected for adventitious carbon contamination on the glass surface.…”

Effects of surface initial condition on aqueous corrosion of glass—A study with a model nuclear waste glass

“…Upon annealing at 550°C for 2 hours, the areal density of BO increases from 8.2/nm 2 to 8.9/nm 2 and the OH concentration decreases from ~4.1/nm 2 to ~2.2/nm 2 . This must be due to the diffusion of the boron and sodium from the bulk and dehydroxylation of the OH species . In other words, it could be said that some defective sites formed during the mechanical polishing are reduced or removed during the annealing process.…”