Publications by Cécile Hébert

A Multiscale Bayesian Approach to Quantification and Denoising of Energy-dispersive X-ray Data

Cécile Hébert, Duncan Thomas Lindsay Alexander

Energy dispersive x-ray (EDX) spectrum imaging yields compositional information with a spatial resolution down to the atomic level. However, experimental limitations often produce extremely sparse and noisy EDX spectra. Under such conditions, every detecte ...

IOP Publishing Ltd2025

Leveraging Machine Learning for Advanced Nanoscale X-ray Analysis: Unmixing Multicomponent Signals and Enhancing Chemical Quantification

Cécile Hébert, Duncan Thomas Lindsay Alexander

Energy dispersive X-ray (EDX) spectroscopy in the transmission electron microscope is a key tool for nanomaterials analysis, providing a direct link between spatial and chemical information. However, using it for precisely determining chemical compositions ...

American Chemical Society (ACS)2024

From STEM-EDXS data to phase separation and quantification using physics-guided NMF

Cécile Hébert, Nathanaël Perraudin, Duncan Thomas Lindsay Alexander, Guillaume Romain Obozinski

We present the development of a new algorithm which combines state-of-the-art energy-dispersive x-ray (EDX) spectroscopy theory and a suitable machine learning formulation for the hyperspectral unmixing of scanning transmission electron microscope EDX spec ...

2024

Non-negative matrix factorization-aided phase unmixing and trace element quantification of STEM-EDXS data

Cécile Hébert, Duncan Thomas Lindsay Alexander, Farhang Nabiei, James Badro

Energy-dispersive X-ray spectroscopy (EDXS) mapping with a scanning transmission electron microscope (STEM) is commonly used for chemical characterization of materials. However, STEM-EDXS quantification becomes challenging when the phases constituting the ...

Elsevier2024

espm: A Python library for the simulation of STEM-EDXS datasets

Cécile Hébert, Nathanaël Perraudin, Duncan Thomas Lindsay Alexander, Hui Chen, Guillaume Romain Obozinski

We present two open-source Python packages: "electron spectro-microscopy"(espm) and "electron microscopy tables"(emtables). The espm software enables the simulation of scanning transmission electron microscopy energy-dispersive X-ray spectroscopy datacubes ...

ELSEVIER2023

Precipitation in lean Mg-Zn-Ca alloys

Cécile Hébert, Davide Deiana

While lean Mg-Zn-Ca alloys are promising materials for temporary implants, questions remain on the impact of Zn and Ca on the microstructure. In this context, the precipitation of Zn and Ca in Mg-1.5Zn-0.25Ca (in wt.%), initially extruded at 330 & DEG;C, t ...

PERGAMON-ELSEVIER SCIENCE LTD2022

3D reconstruction of curvilinear structures with stereo matching deep convolutional neural networks

Pascal Fua, Cécile Hébert, Emad Oveisi, Okan Altingövde, Gulnaz Ganeeva, Anastasiia Mishchuk

Curvilinear structures frequently appear in microscopy imaging as the object of interest. Crystallographic defects, i.e dislocations, are one of the curvilinear structures that have been repeatedly investigated under transmission electron microscopy (TEM) ...

ELSEVIER2022

Investigating Magma Ocean Solidification on Earth Through Laser‐Heated Diamond Anvil Cell Experiments

Marco Cantoni, Cécile Hébert, Philippe Gillet, Farhang Nabiei, James Badro, Charles-Edouard Boukaré

We carried out a series of silicate fractional crystallization experiments at lower mantle pressures using the laser-heated diamond anvil cell. Phase relations and the compositional evolution of the cotectic melt and equilibrium solids along the liquid lin ...

2021

3D Ordering at the Liquid-Solid Polar Interface of Nanowires

Cécile Hébert, Duncan Thomas Lindsay Alexander, Anna Fontcuberta i Morral, Gözde Tütüncüoglu, Nicolas Tappy, Martin George Friedl, Michele Ceriotti, Luca Francaviglia, Giulio Imbalzano, Mahdi Zamani, Lea Ghisalberti, Sara Marti Sanchez

The nature of the liquid-solid interface determines the characteristics of a variety of physical phenomena, including catalysis, electrochemistry, lubrication, and crystal growth. Most of the established models for crystal growth are based on macroscopic t ...

Wiley2020

Triplet grain growth in a-texture polycrystalline ZnO thin films

Arthur Brian Aebersold, Cécile Hébert, Duncan Thomas Lindsay Alexander

A growth of grain triplets is identified in vapor deposited, a-texture polycrystalline zinc oxide thin films, using a combination of transmission electron microscopy-based automated crystal orientation mapping and high-resolution imaging. Each triplet cons ...

2020

Insights into image contrast from dislocations in ADF-STEM

Cécile Hébert, Emad Oveisi, Maria Chiara Spadaro

Competitive mechanisms contribute to image contrast from dislocations in annular dark-field scanning transmission electron microscopy (ADF-STEM). A clear theoretical understanding of the mechanisms underlying the ADF-STEM contrast is therefore essential fo ...

ELSEVIER SCIENCE BV2019

Quantifying competitive grain overgrowth in polycrystalline ZnO thin films

Christophe Ballif, Aïcha Hessler-Wyser, Sylvain Nicolay, Arthur Brian Aebersold, Cécile Hébert, Duncan Thomas Lindsay Alexander, Lorenzo Fanni

2019

Structure and properties of edge dislocations in BiFeO3

Cécile Hébert, Piyush Agrawal, Rolf Erni, Daniele Passerone

Edge dislocations are frequently found in epitaxial BiFeO3 multiferroic thin films and are expected to exhibit distinctive and localized magnetoelectric properties. However, an exhaustive characterization of these dislocations at the atomic level has to da ...

AMER PHYSICAL SOC2019

Evolution of the properties of helium nanobubbles during in situ annealing probed by spectrum imaging in the transmission electron microscope

Cécile Hébert

2018

Three-dimensional scanning transmission electron microscopy of dislocation loops in tungsten

Robin Schäublin, Cécile Hébert, Soheil Hasanzadeh

Scanning transmission electron microscopy (STEM) imaging using diffraction contrast is a powerful technique to assess crystal defects. In this work it is used to assess the spatial distribution of radiation induced defect in tungsten. In effect, its irradi ...

PERGAMON-ELSEVIER SCIENCE LTD2018

A large planetary body inferred from diamond inclusions in a ureilite meteorite

Marco Cantoni, Cécile Hébert, Emad Oveisi, Philippe Gillet, Farhang Nabiei, James Badro, Teresa Katharina Dennenwaldt

Planetary formation models show that terrestrial planets are formed by the accretion of tens of Moon-to Mars-sized planetary embryos through energetic giant impacts. However, relics of these large proto-planets are yet to be found. Ureilites are one of the ...

Nature Research2018

Direct Imaging of Dopant Distribution in Polycrystalline ZnO Films

Christophe Ballif, Aïcha Hessler-Wyser, Sylvain Nicolay, Arthur Brian Aebersold, Cécile Hébert, Duncan Thomas Lindsay Alexander, Stéphane Laurent Escrig, Monica Morales Masis, Martin Ledinsky

Two fundamental requirements of transparent conductive oxides are high conductivity and low optical absorptance, properties strongly dependent on the free-carrier concentration of the film. The free carrier concentration is usually-tuned by the addition of ...

Amer Chemical Soc2017

Zinc blende-wurtzite polytypism in nanocrystalline ZnO films

Christophe Ballif, Aïcha Hessler-Wyser, Sylvain Nicolay, Arthur Brian Aebersold, Cécile Hébert, Duncan Thomas Lindsay Alexander, Lorenzo Fanni

ZnO is commonly observed and assumed to crystallize fully in a wurtzite structure. Indeed, While polytypism between a wurtzite and a zinc blende phase is often seen in some II-VI compounds, it has only rarely been observed in ZnO. Here, by means of automat ...

Elsevier2017

In-Situ Observation of Co-Ce Coated Metallic Interconnect Oxidation Combined with High-Resolution Post Exposure Analysis

Jan Van Herle, Cécile Hébert, Stéphane François Jean Poitel

Oxidation of Sanergy SSHT steel with Ce-Co coating, used as interconnect material, was observed in-situ in a modified environmental scanning electron microscope (ESEM) at nominal temperature between 800°C and 900°C under 33Pa of oxygen, for different durat ...

2017

Properties of helium bubbles in covalent systems at the nanoscale: A combined numerical and experimental study

Cécile Hébert, Duncan Thomas Lindsay Alexander

The properties of nanometric-sized helium bubbles in silicon have been investigated using both spatially resolved electron-energy-loss spectroscopy combined with a recently developed method, and molecular-dynamics simulations. The experiments allowed for a ...

Amer Physical Soc2017