Atom probe tomography

Abstract

The technique of atom probe tomography ͑APT͒ is reviewed with an emphasis on illustrating what is possible with the technique both now and in the future. APT delivers the highest spatial resolution ͑sub-0.3-nm͒ three-dimensional compositional information of any microscopy technique. Recently, APT has changed dramatically with new hardware configurations that greatly simplify the technique and improve the rate of data acquisition. In addition, new methods have been developed to fabricate suitable specimens from new classes of materials. Applications of APT have expanded from structural metals and alloys to thin multilayer films on planar substrates, dielectric films, semiconducting structures and devices, and ceramic materials. This trend toward a broader range of materials and applications is likely to continue.

High-Strength Low-Carbon Ferritic Steel Containing Cu-Fe-Ni-Al-Mn Precipitates

“…[18] The strength of this steel is derived primarily from bcc Cu precipitates, although there is possibly a small contribution from niobiumcarbide (NbC) precipitates at long aging times that delays overaging. [21][22][23] Investigation, by atom-probe tomography (APT) [24][25][26] of the bcc Cu precipitates in a NUCu-100 steel specimen solutionized for 30 minutes at 1100°C and directly aged for 100 minutes at 490°C demonstrated the existence of chemically complex Cu-rich precipitates containing Fe, Ni, Mn, and Al. [27,28] The precipitate/a-Fe matrix heterophase interfaces are enriched in Ni and Mn forming a spherical shell-like structure, whereas the Al enhancement is found toward the inner region of the Cu precipitates.…”

“…This was followed by final electropolishing using a solution of 2 vol pct perchloric acid in butoxyethanol at 8 to 15 Vdc, producing a tip with a radius <50 nm. LEAP and conventional three-dimensional atom-probe (3DAP) tomography [24][25][26] were performed at a specimen temperature of 50 K and a residual pressure of <1 · 10 -8 Pa. The pulse repetition rate was 2 · 10 5 Hz and the pulseto-standing-dc voltage ratio (pulse fraction) was 15 to 20 pct.…”

Topological Data Analysis for the Characterization of Atomic Scale Morphology from Atom Probe Tomography Images

“…Improvements in data collection rates, field-of-view, detection sensitivity (at least one atomic part per million), and specimen preparation have advanced the atom probe from a scientific curiosity to a state-of-the-art research instrument [9][10][11][12][13][14][15][16][17][18]. While APT is a powerful technique with the capacity to gather information containing hundreds of millions of atoms from a single specimen, the ability to effectively use this information has significant challenges.…”

High-resolution 3D analyses of the shape and internal constituents of small volcanic ash particles: The contribution of SEM micro-computed tomography (SEM micro-CT)

“…However, the technical constraints that have to be faced to break the usual spatial resolution limit (possible deformation of the Pt/Ir tip due to heating, decrease of the X-ray flux due to the small size of the X-ray emission volume, practical difficulties in manipulating and centering tiny objects on the sample holder, need for a forward projection procedure to compensate for mechanical inaccuracies of the stage) make it hardly applicable to fine ash (b64 μm; N 4 φ). Other tomographic techniques on the market, such as atom probe tomography (Kelly and Miller, 2007) and electron tomography (Scott et al, 2012), are better suited to achieve unparalleled spatial resolution (down to~2.4 Å), but they are restricted to tiny and needle-shaped objects (b10 −12 mm 3 ), which are orders of magnitude smaller than most fine ash particles. Great expectations are placed in the recently released X-ray nano-CT devices, but the applicability of those instruments in the study of fine ash remains to be tested and validated.…”