Speaker
Description
During the last few decades, Atom Probe Tomography (APT) has proven itself as one of the best material characterization tools due to the combination of atomic resolution and 3D reconstruction capabilities. Still, there are some limitations, as the crystallographic information obtained from APT data is limited. To tackle that issue, a correlative approach of combined Transmission Electron Microscopy (TEM) and APT is often utilized. The limitation of the correlative approach is an increased probability of a sample fracture during transfer and a specimen deterioration due to air exposure. Additionally, the sample is being repeatedly cooled down to cryogenic temperatures and re-heated, resulting in additional contamination. Although, this issue can be addressed by the utilization of cryo-transfer setups [L.Stephenson]. Naturally, the idea to combine APT and TEM in one instrument was stirring the minds of scientist for some time [T.Kelly][T.Kelly]. The work on the project of combining TEM and APT setups in a single instrument began in Groupe de Physique des Matériaux as early as 2014, bearing the name SATMET [W.Lefebvre, ER-C Jülich 2016].
The current generation of SATMET instrument is based on a commercial JEOL F2 TEM equipped with a custom-made straight path APT detection system. To provoke field evaporation a custom-made cryo-specimen holder capable of applying voltage pulses was designed. It allows to perform experiments with the temperature of 78K at the tip position. In addition, the SATMET instrument is equipped with the software to perform 4D-STEM acquisitions. 4D-STEM mapping can be extremely useful to gauge the electric field on the APT tip surface to improve our understand of the field evaporation processes. This talk will illustrate some of the preliminary results obtained on this new tool, merging APT and TEM in a single instrument [G.Da Costa, submitted to Nature Communications 2024].
