High-sensitivity low-energy ion scattering studies of calcium aluminosilicate glass fracture surfaces

Glass surfaces play a critical role in several modern applications, and open questions remain as to how the bulk composition of a multicomponent glass informs its surface composition-particularly at the outermost monolayer. This has important implications for properties such as electrostatic charging, wetting, and adhesion. Here, we apply high-sensitivity low-energy ion scattering (HS-LEIS) to examine a systematic series of ternary CaOAl2O3-SiO2 glass compositions. Analyzed are fresh fracture surfaces created under high-vacuum conditions, giving rigorous attention to peak quantification details. Results indicate that the measured surface compositions are, within uncertainty, very close to analyzed bulk compositions. This finding runs contrary to many studies showing disagreement between surface and bulk composition in glass, and possible reasons are discussed. By providing an experimental foundation from relatively ideal fracture surfaces, these results pave the way for further studies on the outermost composition of realistic glass surfaces of commercial importance.