A Quantitative Investigation of Functionalized Glazing Stacks by Atom Probe Tomography

Insulating glazings used in products for the building and automotive market consist of flat glass with low-emissivity (low-E) coatings. One challenge is to increase the infrared reflectance of the glazing stack while maintaining a high transmittance. This can only be achieved if the chemical interdiffusion between the deposited layers can be controlled and characterized down to the sub-nanometer level. For that, atom probe tomography (APT) is employed in this work; technique which allows a precise quantification of the chemical interdiffusion in 3D and down to sometimes atomic level. However, the APT specimens prepared using the standard top-to-down configuration are prone to systematic fracturing due to strong differences in field evaporation between the layers involved in the glazing stack. The usage of an untypical cross-section configuration has led to improved yields, but for the latter, artifacts need to be considered and quantified. In particular, the effect of artificial layer intermixing at interfaces due to crossover is studied. It is concluded that Ni diffuses in the Ag layer via grain boundaries already in the as-deposited state. Hence, this work opens a new perspective in terms of quantification of interdiffusion at early stages, an important finding for low-E glass applications.