Direct view of the structure of different glass fracture surfaces by atomic force microscopy

Abstract Silica, silicate, borosilicate and heavy metal fluoride glasses were fractured under UHV conditions. The fracture mirror surfaces then were imaged by atomic force microscopy. The atomically resolved images display a fully interconnected random network arrangement for the silica glass, modified random network geometries with percolation paths for the silicate glasses, a structure with higher connectivity with some short percolation paths only for the borosilicate glass and a strongly interconnected structure for the heavy metal fluoride glass, probably with some chain- and ring-like geometric elements. Sodium diffusion, which is supposed to follow mainly these percolation paths, is qualitatively in line with the number, length and width of these paths.