Mining information from atom probe data (original) (raw)
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Dynamic reconstruction for atom probe tomography
2011
Progress in the reconstruction for atom probe tomography has been limited since the first implementation of the protocol proposed by Bas et al. in 1995. This approach and those subsequently developed assume that the geometric parameters used to build the three-dimensional atom map are constant over the course of an analysis. Here, we test this assumption within the analyses of low-alloyed materials. By building upon methods recently proposed to measure the tomographic reconstruction parameters, we demonstrate that this assumption can introduce significant limitations in the accuracy of the analysis. Moreover, we propose a strategy to alleviate this problem through the implementation of a new reconstruction algorithm that dynamically accommodates variations in the tomographic reconstruction parameters.
An Atom-Probe Tomography Primer
MRS Bulletin, 2009
Atom-probe tomography (APT) is in the midst of a dynamic renaissance as a result of the development of well-engineered commercial instruments that are both robust and ergonomic and capable of collecting large data sets, hundreds of millions of atoms, in short time periods compared to their predecessor instruments. An APT setup involves a field-ion microscope coupled directly to a special time-of-flight (TOF) mass spectrometer that permits one to determine the mass-to-charge states of individual field-evaporated ions plus their x-, y-, and z-coordinates in a specimen in direct space with subnanoscale resolution. The three-dimensional (3D) data sets acquired are analyzed using increasingly sophisticated software programs that utilize high-end workstations, which permit one to handle continuously increasing large data sets. APT has the unique ability to dissect a lattice, with subnanometer-scale spatial resolution, using either voltage or laser pulses, on an atom-by-atom and atomic pla...
2018
Atom probe tomography (APT) represents a revolutionary characterization tool for materials that combine atomic imaging with a time-of-flight (TOF) mass spectrometer to provide direct space three-dimensional, atomic scale resolution images of materials with the chemical identities of hundreds of millions of atoms. It involves the controlled removal of atoms from a specimen’s surface by field evaporation and then sequentially analyzing them with a position sensitive detector and TOF mass spectrometer. A paradox in APT is that while on the one hand, it provides an unprecedented level of imaging resolution in three dimensions, it is very difficult to obtain an accurate perspective of morphology or shape outlined by atoms of similar chemistry and microstructure. The origins of this problem are numerous, including incomplete detection of atoms and the complexity of the evaporation fields of atoms at or near interfaces. Hence, unlike scattering techniques such as electron microscopy, inter...
Characterizing the Spatial Behavior of Multiple Detection Events in Atom Probe Tomography
2016
Atom probe tomography is a cornerstone of modern materials characterization, which commonly requires spatial and chemical information at the nanoscale. The reconstructed data sets produced often reveal detailed information about the material structure, but much more can be obtained by looking at the spatial correlations and ancillary data. Here, the spatial information contained in multiple detection events (MDEs) is examined to understand their behavior and origins via subsetting by multiplicity and sampling from these subsets. It is shown that MDEs are highly spatially clustered, and a model of their production is developed based upon a Neyman-Scott process of fixed cluster event count. The model uses only the cluster process count as a parameter and shows significant agreement across a range of MDE orders, indicating that MDEs are governed by the same underlying process.