Enabling near-atomic–scale analysis of frozen water

Transmission electron microscopy went through a revolution enabling routine cryo-imaging of biological and (bio)chemical systems, in liquid form. Yet, these approaches typically lack advanced analytical capabilities. Here, we used atom probe tomography to analyze frozen liquids in three dimensions with subnanometer resolution. We introduce a specimen preparation strategy using nanoporous gold. We report data on 2- to 3-μm-thick layers of ice formed from both high-purity deuterated water and a solution of 50 mM NaCl in high-purity deuterated water. The analysis of the gold-ice interface reveals a substantial increase in the solute concentrations across the interface. We explore a range of experimental parameters to show that atom probe analyses of bulk aqueous specimens come with their own challenges and discuss physical processes that produce the observed phenomena. Our study demonstrates the viability of using frozen water as a carrier for near-atomic–scale analysis of objects in solution by atom probe tomography.

Download Full-text

Challenges Associated with the Characterisation of Nanocrystalline Materials Using Atom Probe Tomography

Materials Science Forum ◽

10.4028/www.scientific.net/msf.654-656.2366 ◽

2010 ◽

Vol 654-656 ◽

pp. 2366-2369 ◽

Cited By ~ 4

Author(s):

Feng Zai Tang ◽

Talukder Alam ◽

Michael P. Moody ◽

Baptiste Gault ◽

Julie M. Cairney

Keyword(s):

Quantitative Analysis ◽

Atom Probe Tomography ◽

Nanocrystalline Materials ◽

Atom Probe ◽

Atomic Scale ◽

Three Dimensions ◽

Specimen Preparation ◽

Compositional Information

Atom probe tomography provides compositional information in three dimensions at the atomic scale, and is therefore extremely suited to the study of nanocrystalline materials. In this paper we present atom probe results from the investigation of nanocomposite TiSi¬Nx coatings and nanocrystalline Al. We address some of the major challenges associated with the study of nanocrystalline materials, including specimen preparation, visualisation, common artefacts in the data and approaches to quantitative analysis. We also discuss the potential for the technique to relate crystallographic information to the compositional maps.

Download Full-text

Origins of the hydrogen signal in atom probe tomography: Case studies of alkali and noble metals

New Journal of Physics ◽

10.1088/1367-2630/ac40cd ◽

2021 ◽

Author(s):

Su-Hyun Yoo ◽

Se-Ho Kim ◽

Eric Woods ◽

Baptiste Gault ◽

Mira Todorova ◽

...

Keyword(s):

Atom Probe Tomography ◽

Density Functional ◽

Noble Metals ◽

Alkali Metals ◽

Atom Probe ◽

Operating Conditions ◽

Atomic Scale ◽

Three Dimensions ◽

High Signal ◽

Specimen Preparation

Abstract Atom Probe Tomography (APT) analysis is being actively used to provide near-atomic-scale information on the composition of complex materials in three-dimensions. In recent years, there has been a surge of interest in the technique to investigate the distribution of hydrogen in metals. However, the presence of hydrogen in the analysis of almost all specimens from nearly all material systems has caused numerous debates as to its origins and impact on the quantitativeness of the measurement. It is often perceived that most H arises from residual gas ionization, therefore affecting primarily materials with a relatively low evaporation field. In this work, we perform systematic investigations to identify the origin of H residuals in APT experiments by combining density-functional theory (DFT) calculations and APT measurements on an alkali and a noble metal, namely Na and Pt, respectively. We report that no H residual is found in Na metal samples, but in Pt, which has a higher evaporation field, a relatively high signal of H is detected. These results contradict the hypothesis of the H signal being due to direct ionization of residual H2 without much interaction with the specimen's surface. Based on DFT, we demonstrate that alkali metals are thermodynamically less likely to be subject to H contamination under APT-operating conditions compared to transition or noble metals. These insights indicate that the detected H-signal is not only from ionization of residual gaseous H2 alone, but is strongly influenced by material-specific physical properties. The origin of H residuals is elucidated by considering different conditions encountered during APT experiments, specifically, specimen-preparation, transportation, and APT-operating conditions by taking thermodynamic and kinetic aspects into account.

Download Full-text

Reflections on the Analysis of Interfaces and Grain Boundaries by Atom Probe Tomography

Microscopy and Microanalysis ◽

10.1017/s1431927620000197 ◽

2020 ◽

Vol 26 (2) ◽

pp. 247-257 ◽

Cited By ~ 1

Author(s):

Benjamin M. Jenkins ◽

Frédéric Danoix ◽

Mohamed Gouné ◽

Paul A.J. Bagot ◽

Zirong Peng ◽

...

Keyword(s):

Grain Boundaries ◽

Atom Probe Tomography ◽

Compositional Analysis ◽

Atom Probe ◽

Atomic Scale ◽

Three Dimensions ◽

Specimen Preparation ◽

Structure Property ◽

Wide Range

AbstractInterfaces play critical roles in materials and are usually both structurally and compositionally complex microstructural features. The precise characterization of their nature in three-dimensions at the atomic scale is one of the grand challenges for microscopy and microanalysis, as this information is crucial to establish structure–property relationships. Atom probe tomography is well suited to analyzing the chemistry of interfaces at the nanoscale. However, optimizing such microanalysis of interfaces requires great care in the implementation across all aspects of the technique from specimen preparation to data analysis and ultimately the interpretation of this information. This article provides critical perspectives on key aspects pertaining to spatial resolution limits and the issues with the compositional analysis that can limit the quantification of interface measurements. Here, we use the example of grain boundaries in steels; however, the results are applicable for the characterization of grain boundaries and transformation interfaces in a very wide range of industrially relevant engineering materials.

Download Full-text