NU Center for Atom Probe Tomography

Atom Probe Tomography (APT) produces a three-dimensional (3D) atom-by-atom image of a sample, with sub-nanometer spatial resolution and a typically 150 x 150 x 500 nm^3 analyzed volume, by simultaneous high resolution imaging and time of flight mass spectrometry. APT is particularly suited to study nano or nanostructured materials. The same samples can also be characterized by Transmission Electron Microscopy (TEM), in a correlative study. To compare these experimental results with atomistic simulations on the same size scale, ab-initio calculations and Monte-Carlo simulations can be performed at our facility. NUCAPT operates a CAMECA LEAP 5000XS tomograph. Specimen tips can be prepared by electropolishing (metals) and from almost any material by FIB (Focused-ion beam milling ). Ion beam sputter deposition creates thin film structures that aid with APT specimen preparation. Vacuum arc melting systems are available for syntesizing alloys and compounds. Thermocalc and MEDEA software packages are available for thermodynamic calculations and materials simulations.