Leigh T. Stephenson's research while affiliated with Max Planck Institute for Iron Research GmbH and other places

Publications (111)

Preprint
Gas-solid reactions are cornerstones of many catalytic and redox processes that will underpin the energy and sustainability transition. The specific case of hydrogen-based iron oxide reduction is the foundation to render the global steel industry fossil-free, an essential target as iron production is the largest single industrial emitter of carbon...
Article
The eutectic Ga-In (EGaIn) alloy has low vapor pressure, low toxicity, high thermal and electrical conductivities, and thus has shown a great potential for smart material applications. For such applications, EGaIn is maintained above its melting point, below which it undergoes solidification and phase separation. A scientific understanding of the s...
Article
The selective removal of a less noble (more chemically active) metal from a mixture of 2–3 metals can yield a bicontinuous, open-pore, 3D nanoporous metal (NPM), that is rich in the more noble metal(s) ¹ . NPMs have been successfully developed by the intelligent use of the conventionally-undesired dealloying corrosion. The excellent properties of N...
Preprint
Full-text available
Identifying the chemical and bonding state of all atoms in a material in three-dimensions remains an unresolved issue. Here, we demonstrate that this information was always intrinsically present within atom probe tomography experimental data, but until now it was overlooked or consciously suppressed. Using an analytical model and robust simulations...
Preprint
Full-text available
The upcoming flexible ultra-thin glass for foldable displays has attracted widespread attention as an alternative to rigid electronic smartphones. However, the detailed compositional effect of the chemical strengthening of the glass is not well understood. The spatially resolved chemistry and the depth of compression layer of tempered glass is far...
Article
Full-text available
Hydrogen embrittlement can cause a dramatic deterioration of the mechanical properties of high-strength metallic materials. Despite decades of experimental and modelling studies, the exact underlying mechanisms behind hydrogen embrittlement remain elusive. To unlock understanding of the mechanism and thereby help mitigate the influence of hydrogen...
Article
Full-text available
Numerous metallurgical and materials science applications depend on quantitative atomic-scale characterizations of environmentally-sensitive materials and their transient states. Studying the effect upon materials subjected to thermochemical treatments in specific gaseous atmospheres is of central importance for specifically studying a material’s r...
Article
Full-text available
The worldwide development of electric vehicles as well as large-scale or grid-scale energy storage to compensate for the intermittent nature of renewable energy generation has led to a surge of interest in battery technology. Understanding the factors controlling battery capacity and, critically, their degradation mechanisms to ensure long-term, su...
Article
Full-text available
Imaging of liquids and cryogenic biological materials by electron microscopy has been recently enabled by innovative approaches for specimen preparation and the fast development of optimized instruments for cryo-enabled electron microscopy (cryo-EM). Yet, cryo-EM typically lacks advanced analytical capabilities, in particular for light elements. Wi...
Preprint
Full-text available
Chemical short-range order (CSRO) refers to atoms of specific elements self-organising within a disordered crystalline matrix. These particular atomic neighbourhoods can modify the mechanical and functional performances of materials 1-6. CSRO is typically characterized indirectly, using volume-averaged (e.g. X-ray/neutron scattering) 2,7,8 or throu...
Article
Full-text available
Metal nanogels combine a large surface area, a high structural stability, and a high catalytic activity toward a variety of chemical reactions. Their performance is underpinned by the atomic-level distribution of their constituents, yet analyzing their subnanoscale structure and composition to guide property optimization remains extremely challengi...
Article
Full-text available
Atom probe tomography (APT) is often introduced as providing “atomic-scale” mapping of the composition of materials and as such is often exploited to analyze atomic neighborhoods within a material. Yet quantifying the actual spatial performance of the technique in a general case remains challenging, as it depends on the material system being invest...
Article
Hydrogen embrittlement can cause a dramatic deterioration of the mechanical properties of high-strength metallic materials. Despite decades of experimental and modelling studies, the exact underlying mechanisms behind hydrogen embrittlement remain elusive. To unlock understanding of the mechanism and thereby help mitigate the influence of hydrogen...
Preprint
Full-text available
The worldwide developments of electric vehicles, as well as large-scale or grid-scale energy storage to compensate the intermittent nature of renewable energy generation has generated a surge of interest in battery technology. Understanding the factors controlling battery capacity and, critically, their degradation mechanisms to ensure long-term, s...
Preprint
Full-text available
Hydrogen embrittlement can cause a dramatic deterioration of the mechanical properties of high-strength metallic materials. Despite decades of experimental and modelling studies, the exact underlying mechanisms behind hydrogen embrittlement remain elusive. To unlock understanding of the mechanism and thereby help mitigate the influence of hydrogen...
Article
Three-dimensional field ion microscopy is a powerful technique to analyze material at a truly atomic scale. Most previous studies have been made on pure, crystalline materials such as tungsten or iron. In this article, we study more complex materials, and we present the first images of an amorphous sample, showing the capability to visualize the co...
Article
Atom probe tomography (APT) helps elucidate the link between the nanoscale chemical variations and physical properties, but it has a limited structural resolution. Field ion microscopy (FIM), a predecessor technique to APT, is capable of attaining atomic resolution along certain sets of crystallographic planes albeit at the expense of elemental ide...
Preprint
Full-text available
Quantitative characterization of environmentally-sensitive materials and their transient states after being subjected to thermal treatment in specific gaseous atmospheres at near-atomic scales is of vital importance for numerous metallurgical and materials science applications, such as corrosion, hydrogen embrittlement, catalysis, reduction and sur...
Preprint
Full-text available
Metal nano-aerogels combine a large surface area, a high structural stability, and a high catalytic activity towards a variety of chemical reactions. The performance of such nanostructures is underpinned by the atomic-level distribution of their constituents. Yet monitoring their sub-nanoscale structure and composition to guide property optimizatio...
Preprint
Full-text available
Owing to its low vapor pressure, low toxicity, high thermal and electrical conductivities, eutectic Ga-In (EGaIn) has shown a great potential for smart material applications in flexible devices, cooling in micro-devices, self-healing reconfigurable materials, and actuators. For such applications, EGaIn is maintained above its melting point, below w...
Preprint
Full-text available
Steel is the most important material class in terms of volume and environmental impact. While it is a sustainability enabler, for instance through lightweight design, magnetic devices, and efficient turbines, its primary production is not. Iron is reduced from ores by carbon, causing 30% of the global CO 2 emissions in manufacturing , qualifying it...
Article
It is know from literature that small additions (<1 wt%) of Ca, Al and Zn significantly improve the intrinsic ductility of Mg. The exact role of each element, both qualitatively and quantitatively, and their combined effects, however, are poorly understood. Here we achieved a much clearer view on the quantitative role of each element with respect t...
Article
Steel is the most important material class in terms of volume and environmental impact. While it is a sustainability enabler, for instance through lightweight design, magnetic devices, and efficient turbines, its primary production is not. Iron is reduced from ores by carbon, causing 30% of the global CO2 emissions in manufacturing, qualifying it a...
Preprint
Atom probe tomography (APT) helps elucidate the link between the nanoscale chemical variations and physical properties, but it has limited structural resolution. Field ion microscopy (FIM), a predecessor technique to APT, is capable of attaining atomic resolution along certain sets of crystallographic planes albeit at the expense of elemental ident...
Preprint
Full-text available
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 investigat...
Preprint
Full-text available
Imaging individual vacancies in solids and revealing their interactions with solute atoms remains one of the frontiers in microscopy and microanalysis. Here we study a creep-deformed binary Ni-2 at.% Ta alloy. Atom probe tomography reveals a random distribution of Ta. Field ion microscopy, with contrast interpretation supported by density-functiona...
Preprint
Full-text available
Nanoscale L12-type ordered structures are widely used in face-centred cubic (FCC) alloys to exploit their hardening capacity and thereby improve mechanical properties. These fine-scale particles are typically fully coherent with matrix with the same atomic configuration disregarding chemical species, which makes them challenging to be characterized...
Preprint
The incorporation of impurities during the chemical synthesis of nanomaterials is usually uncontrolled and rarely reported because of the formidable challenge that constitutes measuring trace amounts of often light elements with sub nanometre spatial resolution. Yet these foreign elements influence functional properties, by e.g. doping. Here we dem...
Preprint
Pinning-type magnets maintaining high coercivity, i.e. the ability to sustain magnetization, at high temperature are at the core of thriving clean-energy technologies. Among these, Sm2Co17-based magnets are excellent candidates owing to their high-temperature stability. However, despite decades of efforts to optimize the intragranular microstructur...
Preprint
Molybdenum disulfide (MoS$_2$) nanosheet is a two-dimensional material with high electron mobility and with high potential for applications in catalysis and electronics. We synthesized MoS$_2$ nanosheets using a one-pot wet-chemical synthesis route with and without Re-doping. Atom probe tomography revealed that 3.8 at.% Re is homogeneously distribu...
Preprint
With 1.85 billion tons produced per year, steel is the most important material class in terms of volume and environmental impact. While steel is a sustainability enabler, for instance through lightweight design, magnetic devices, and efficient turbines, its primary production is not. For 3000 years, iron has been reduced from ores using carbon. Tod...
Article
Full-text available
Pinning‐type magnets with high coercivity at high temperatures are at the core of thriving clean‐energy technologies. Among these, Sm2Co17‐based magnets are excellent candidates owing to their high‐temperature stability. However, despite intensive efforts to optimize the intragranular microstructure, the coercivity currently only reaches 20–30% of...
Preprint
Imaging of liquids and cryogenic biological materials by electron microscopy has been recently enabled by innovative approaches for specimen preparation and the fast development of optimised instruments for cryo-enabled electron microscopy (cryo-EM). Yet, Cryo-EM typically lacks advanced analytical capabilities, in particular for light elements. Wi...
Article
The long-term safety of water-based nuclear reactors relies in part on the reliability of zirconium-based nuclear fuel cladding. Yet the progressive ingress of hydrogen during service makes zirconium alloys subject to delayed hydride cracking. Here, we use a combination of electron back-scattered diffraction and atom probe tomography to investigate...
Article
Full-text available
Nanoscale L12-type ordered structures are widely used in face-centered cubic (FCC) alloys to exploit their hardening capacity and thereby improve mechanical properties. These fine-scale particles are typically fully coherent with matrix with the same atomic configuration disregarding chemical species, which makes them challenging to be characterize...
Article
Full-text available
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 specim...
Article
Atom probe tomography (APT) is particularly suited for the analysis of nanoscale microstructural features in metallic alloys. APT has become important in the quantitative assessment at high spatial resolution of light elements, which are notoriously difficult to analyze by electron- or X-ray-based techniques. These control the physical properties o...
Preprint
The long-term safety of water-based nuclear reactors relies in part on the reliability of zirconium-based nuclear fuel. Yet the progressive ingress of hydrogen during service makes zirconium alloys subject to delayed hydride cracking. Here, we use a combination of electron back-scattered diffraction and atom probe tomography to investigate specific...
Article
Full-text available
The properties of a material can be engineered by manipulating its atomic and chemical architecture. Nanoglasses which have been recently invented and comprise nanosized glassy particles separated by amorphous interfaces, have shown promising properties. A potential way to exploit the structural benefits of nanoglasses and of nanocrystalline materi...
Preprint
Observing solute hydrogen (H) in matter is a formidable challenge, yet, enabling quantitative imaging of H at the atomic-scale is critical to understand its deleterious influence on the mechanical strength of many metallic alloys that has resulted in many catastrophic failures of engineering parts and structures. Here, we report on the APT analysis...
Article
Application of SIMS and APT to Understand Scale Dependent U-Pb Isotope Behavior in Zircon - Tyler Blum, John Valley, Baptiste Gault, Leigh Stephenson
Preprint
Full-text available
Transmission electron microscopy has undergone a revolution in recent years with the possibility to perform routine cryo-imaging of biological materials and (bio)chemical systems, as well as the possibility to image liquids via dedicated reaction cells or graphene-sandwiching. These approaches however typically require imaging a large number of spe...
Article
Full-text available
Molybdenum disulfide (MoS2) nanosheet is a two‐dimensional (2D) material with high electron mobility and with high potential for applications in catalysis and electronics. MoS2 nanosheets are synthesized using a one‐pot wet‐chemical synthesis route with and without Re doping. Atom probe tomography reveals that 3.8 at% Re is homogeneously distribute...
Article
Observing solute hydrogen (H) in matter is a formidable challenge, yet, enabling quantitative imaging of H at the atomic-scale is critical to understand its deleterious influence on the mechanical strength of many metallic alloys that has resulted in many catastrophic failures of engineering parts and structures. Here, we report on the APT analysis...
Article
Full-text available
The incorporation of impurities during the chemical synthesis of nanomaterials is usually uncontrolled and rarely reported because of the formidable challenge that constitutes measuring trace amounts of often light elements with sub nanometre spatial resolution. Yet these foreign elements influence functional properties, by e.g. doping. Here we dem...
Article
Full-text available
Fehlerkartierung: Die Charakterisierung von Verunreinigungen ist der Schlüssel zum Verständnis der funktionellen Eigenschaften von Nanomaterialien. Die Struktur‐Eigenschafts‐Beziehungen von partiell reduzierten hohlen TiO2‐Nanodrähten wurden mithilfe von Raster‐TEM und Atomsonden‐Tomographie erforscht. Sauerstoffleerstellen und unerwünschte Bor‐, N...
Article
We combined experimental investigations and theoretical calculations to unveil an abnormal magnetic behavior caused by addition of the nonmagnetic element Cu in face-centered-cubic FeNiCoMn-based high-entropy alloys (HEAs). Upon Cu addition, the probed HEAs show an increase of both Curie temperature and saturation magnetization in as-cast and homog...
Article
Full-text available
Directly imaging all atoms constituting a material and, maybe more importantly, crystalline defects that dictate materials’ properties, remains a formidable challenge. Here, we propose a new approach to chemistry-sensitive field-ion microscopy (FIM) combining FIM with time-of-flight mass-spectrometry ( tof-ms ). Elemental identification and correla...
Article
Full-text available
Quantification of Solute Deuterium in Titanium Deuteride by Atom Probe Tomography with Both Laser Pulsing and High-Voltage Pulsing: Influence of the Global and Local Surface Electric Field - Volume 25 Supplement - Y. H. Chang, I. Mouton, L. Stephenson, M. Ashton, G. K. Zhang, A. Szczpaniak, D. Ponge, D. Raabe, B. Gault
Article
Hydride Growth Mechanism in Zircaloy-4: Investigation of the Partitioning of Alloying Elements - Volume 25 Supplement - Isabelle Mouton, Yanhong Chang, Siyang Wang, Andrew J. Breen, Agnieszka Szczepaniak, Leigh T. Stephenson, Dierk Raabe, T. Ben Britton, Baptiste Gault
Article
An Atomic Renaissance For Pulsed Field Ion Microscopy - Volume 25 Supplement - Shyam Katnagallu, Isabelle Mouton, Felipe Oliveira, Baptiste Gault, Dierk Raabe, Leigh T. Stephenson
Article
Direct Observation of Hydrogen in Cold-Drawn Pearlitic Steel Wires Using Cryogenic Atom Probe Tomography - Volume 25 Supplement - Andrew J Breen, Yujiao Li, Leigh Stephenson, Baptiste Gault, Michael Herbig
Article
Full-text available
Hough Transform Based Accurate Composition Extractions From Correlation Histograms in Atom Probe Tomography - Volume 25 Supplement - Mozhdeh Fathidoost, Leigh Stephenson, Dierk Raabe, Baptiste Gault, Shyam Katnagallu
Article
Full-text available
Atom probe tomography (APT) has been increasingly used to investigate hydrogen embrittlement in metals due to its unique capacity for direct imaging of H atoms interacting with microstructural features. The quantitativeness of hydrogen measurements by APT is yet to be established in views of erroneous compositional measurements of bulk hydrides and...
Article
Analysis and understanding of the role of hydrogen in metals is a significant challenge for the future of materials science, and this is a clear objective of recent work in the atom probe tomography (APT) community. Isotopic marking by deuteration has often been proposed as the preferred route to enable quantification of hydrogen by APT. Zircaloy-4...
Preprint
Full-text available
Directly imaging all atoms constituting a material and, maybe more importantly, crystalline defects that dictate materials' properties, remains a formidable challenge. Here, we propose a new approach to chemistry-sensitive field-ion microscopy (FIM) combining contrast interpretation from density-functional theory (DFT) and elemental identification...
Article
Full-text available
Hydrogen pickup leading to hydride formation is often observed in commercially pure Ti (CP-Ti) and Ti-based alloys prepared for microscopic observation by conventional methods, such as electro-polishing and room temperature focused ion beam (FIB) milling. Here, we demonstrate that cryogenic FIB milling can effectively prevent undesired hydrogen pic...
Article
Although atom probe tomography (APT) reconstructions do not directly influence the local elemental analysis, any structural inferences from APT volumes demand a reliable reconstruction of the point cloud. Accurate estimation of the reconstruction parameters is crucial to obtain reliable spatial scaling. In the current work, a new automated approach...
Article
Full-text available
Ingress of hydrogen is often linked to catastrophic failure of Ti-alloys. Here, we quantify the hydrogen distribution in fully \b{eta} and {\alpha}+\b{eta} Ti-Mo alloys by using atom probe tomography. Hydrogen does not segregate at grain boundaries in the fully \b{eta} sample but segregates at some {\alpha}/\b{eta} phase boundaries with a compositi...
Article
Ingress of hydrogen is often linked to catastrophic failure of Ti-alloys. Here, we quantify the hydrogen distribution in fully β and α + β Ti\ \Mo alloys by using atom probe tomography. Hydrogen does not segregate at grain boundaries in the fully β sample but segregates at some α/β phase boundaries with a composition exceeding 20 at.% in the α + β...
Article
Full-text available
Amyloid-beta (Ab) proteins play an important role in a number of neurodegenerative diseases. Ab is found in senile plaques in brains of Alzeimer’s disease patients. The 42 residues of the monomer form dimers which stack to fibrils gaining several micrometers in length. Using Ab fibrils with ¹³C and ¹⁵N marker substitution, we developed an innovativ...
Article
Full-text available
Atom probe tomography (APT) is rising in influence across many parts of materials science and engineering thanks to its unique combination of highly sensitive composition measurement and three-dimensional microstructural characterization. In this invited article, we have selected a few recent applications that showcase the unique capacity of APT to...
Preprint
Analysis and understanding of the role of hydrogen in metals is a significant challenge for the future of materials science, and this is a clear objective of recent work in the atom probe tomography (APT) community. Isotopic marking by deuteration has often been proposed as the preferred route to enable quantification of hydrogen by APT. Zircaloy-4...
Article
The aging response of two Al-3Mg alloys with Cu addition < 1 wt% has been tracked under simulated automotive paint bake conditions ($ 20 min, 160 and 200 C) to quantify the processes controlling hardening. The decomposition of the solid solution, observed by atom probe tomography, has been interpreted using a novel pair correlation function approac...
Article
The aging response of two Al-3Mg alloys with Cu addition < 1 wt% has been tracked under simulated automotive paint bake conditions ($ 20 min, 160 and 200 C) to quantify the processes controlling hardening. The decomposition of the solid solution, observed by atom probe tomography, has been interpreted using a novel pair corr