Atom probe tomography (APT) is routinely used for analyzing property-enhancing particles in the nanometer-size range and below, and plays a prominent role in the analysis of solute clusters. However, the question of how well these small particles are measured has never been addressed because of a lack of a reliable benchmark. Here, to address this critical gap, we use an approach that allows direct comparison of APT and small-angle (X-Ray) scattering (SA(X)S) performed on the same material. Our results demonstrate that the size and composition of particles with a radius below \SI{1}{\nano\meter} (\textapprox\num{250} atoms) cannot be accurately measured, even though the particles are detected. We introduce the notion of an effective spatial resolution for the analysis of particles, which, importantly in this context, is very different than the technique's inherent spatial resolution. This thorough metrological assessment of APT in the analysis of particles allows us to discuss the pulse spread function of the technique and the reasons underpinning its limits. We conclude that great care should be taken when analysing solute clusters by APT, in particular when reporting particle size and composition.

中文翻译：

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通过原子探针断层扫描测量小颗粒和溶质簇

原子探针断层扫描 (APT) 通常用于分析纳米级及以下的性能增强粒子，并在溶质簇的分析中发挥重要作用。然而，由于缺乏可靠的基准，这些小颗粒的测量效果问题从未得到解决。在这里，为了解决这一关键差距，我们使用了一种方法，可以直接比较在同一材料上执行的 APT 和小角度（X 射线）散射 (SA(X)S)。我们的结果表明，即使检测到粒子，半径低于 \SI{1}{\nano\meter}（\textapprox\num{250} 个原子）的粒子的大小和组成也无法准确测量。我们引入了用于分析粒子的有效空间分辨率的概念，在这种情况下，重要的是，与该技术固有的空间分辨率非常不同。这种在粒子分析中对 APT 的彻底计量评估使我们能够讨论该技术的脉冲扩散函数及其限制的原因。我们得出的结论是，在通过 APT 分析溶质簇时应格外小心，尤其是在报告粒径和组成时。