Reflections on the spatial performance of atom probe tomography in the analysis of atomic neighbourhoods

TL;DR

This paper critically examines the spatial resolution limits of atom probe tomography in analyzing atomic neighborhoods across various materials, emphasizing the importance of understanding these limitations for accurate interpretation.

Contribution

It provides a comparative analysis using experiments and simulations to evaluate the spatial performance of atom probe tomography in different material systems.

Findings

Spatial resolution limits vary with material and specimen geometry.

Directional neighborhood analysis is more robust than full 3D analysis.

The study encourages reflective practices within the atom probe community.

Abstract

Atom probe tomography is often introduced as providing "atomic-scale" mapping of the composition of materials and as such is often exploited to analyse atomic neighbourhoods within a material. Yet quantifying the actual spatial performance of the technique in a general case remains challenging, as they depend on the material system being investigated as well as on the specimen's geometry. Here, by using comparisons with field-ion microscopy experiments and field-ion imaging and field evaporation simulations, we provide the basis for a critical reflection on the spatial performance of atom probe tomography in the analysis of pure metals, low alloyed systems and concentrated solid solutions (i.e. akin to high-entropy alloys). The spatial resolution imposes strong limitations on the possible interpretation of measured atomic neighbourhoods, and directional neighbourhood analyses restricted to the depth are expected to be more robust. We hope this work gets the community to reflect on its practices, in the same way, it got us to reflect on our work.