TY - JOUR
T1 - Low-Energy Ion Scattering spectroscopy of silicate glass surfaces
AU - Almeida, Rui M.
AU - Hickey, Ray
AU - Jain, Himanshu
AU - Pantano, Carlo G.
N1 - Funding Information:
Rui Almeida would like to thank IMI-NFG and Lehigh University for its hospitality during a sabbatical leave from IST (Lisbon) in the academic year of 2011–2012. This work was supported by NSF through IMI-NFG grant DMR-0844014 .
PY - 2014
Y1 - 2014
N2 - Low-Energy Ion Scattering (LEIS) spectroscopy is a technique with a unique sensitivity to the elemental composition of the surface top atomic layers of a solid. LEIS measurements of simple binary silicate glasses (with Na 2O, Cs2O or BaO) have shown differences in composition between the as-cast glass surface and the vacuum-fracture surface. The as-cast surface is usually depleted of modifier ions compared to the nominal (batch) bulk glass composition, while the fracture surface is typically enriched with the monovalent modifier species, but not the divalent barium. While the melt surface depletion can probably be attributed to evaporation from the hot melt surface, the origin of the strong accumulation on the fracture surfaces is less clear. It is certainly possible that the fracture may have been preferentially guided by regions already alkali-enriched within the bulk of the glass. But considering the extreme surface sensitivity of this method, a surface-monolayer localized enrichment with alkali due to the stress gradient created by the fracture or the electric field created by dangling bonds on the vacuum-fractured surface is also possible. The Si/O ratio shows usually little deviation from the nominal glass batch value, falling within the estimated errors.
AB - Low-Energy Ion Scattering (LEIS) spectroscopy is a technique with a unique sensitivity to the elemental composition of the surface top atomic layers of a solid. LEIS measurements of simple binary silicate glasses (with Na 2O, Cs2O or BaO) have shown differences in composition between the as-cast glass surface and the vacuum-fracture surface. The as-cast surface is usually depleted of modifier ions compared to the nominal (batch) bulk glass composition, while the fracture surface is typically enriched with the monovalent modifier species, but not the divalent barium. While the melt surface depletion can probably be attributed to evaporation from the hot melt surface, the origin of the strong accumulation on the fracture surfaces is less clear. It is certainly possible that the fracture may have been preferentially guided by regions already alkali-enriched within the bulk of the glass. But considering the extreme surface sensitivity of this method, a surface-monolayer localized enrichment with alkali due to the stress gradient created by the fracture or the electric field created by dangling bonds on the vacuum-fractured surface is also possible. The Si/O ratio shows usually little deviation from the nominal glass batch value, falling within the estimated errors.
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U2 - 10.1016/j.jnoncrysol.2013.11.020
DO - 10.1016/j.jnoncrysol.2013.11.020
M3 - Article
AN - SCOPUS:84888857414
SN - 0022-3093
VL - 385
SP - 124
EP - 128
JO - Journal of Non-Crystalline Solids
JF - Journal of Non-Crystalline Solids
ER -