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Preferential evaporation in atom probe tomography: an analytical approach

Atom probe tomography (APT) analysis conditions play a major role in the composition measurement accuracy. Preferential evaporation, which significantly biases apparent composition, more than other well-known phenomena in APT, is strongly connected to those analysis conditions. One way to optimize them, in order to have the most accurate measurement, is therefore to be able to predict and then to estimate their influence on the apparent composition. An analytical model is proposed to quantify the preferential evaporation. This model is applied to three different alloys: NiCu, FeCrNi and FeCu. The model explains not only the analysis temperature dependence, as in already existing model, but also the dependence to the pulse fraction and the pulse frequency. Moreover, the model can also provide energetic constant directly linked to energy barrier, required to field evaporate atom from the sample surface. 2