Depth profiling analysis of lithium and barium disilicate coatings on silica glass

Abstract

The electron gas secondary neutral mass spectrometry, operated in the high-frequency mode, is especially suitable for the analysis of electrically insulating materials. This is demonstrated for the sol-gel coating Systems Li₂O · 2 SiO₂ and BaO · 2 SiO₂ on silica glass Substrates as examples. The Li₂O · 2 SiO₂ coating is crystalline and displays fluctuations in composition and/or phases. This heterogeneity is confirmed on atomic force microscope Images. Depending on heat treatment the BaO · 2 SiO₂ coatings are glassy and crystalline, respectively. They do not show any fluctuations; however, the depth profiles display some AI₂O₃ having diffused from the silica Substrates into the films during sol-gel consolidadon. Atomic force microscope Images reveal grooves in the Substrate surfaces in which AI₂O₃ remnants of the grinding process have been captured. The depth of the AI₂O₃ profile from the SNMS measurement corresponds to the depth of Channels found using the atomic force microscope. It is assumed that AI₂O₃ originates from remnants of the grinding material used to produce the silica Substrates.