Publications de Duncan Thomas Lindsay Alexander

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

Engineering Symmetry Breaking Interfaces by Nanoscale Structural-Energetics in Orthorhombic Perovskite Thin Films

Duncan Thomas Lindsay Alexander, Bernat Mundet

The atomic configuration of phases and their interfaces is fundamental to materials design and engineering. Here, we unveil a transition metal oxide interface, whose formation is driven by energetic influences─epitaxial tensile strain versus oxygen octahed ...

2025

Investigating domain structures and superdomains in ferroelectric PbTiO3 based heterostructures on DyScO3

Duncan Thomas Lindsay Alexander

This work focuses on the complex ferroelastic/ferroelectric domain structure in the prototypical ferroelectric PbTiO3 epitaxially strained on (110)o-oriented DyScO3 substrates, with a 22 nm-thick bottom SrRuO3 electrode. High quality epitaxial growth has b ...

2025

Synaptic and neuronal functionalities on a single oxide film via interface engineering

Duncan Thomas Lindsay Alexander

Achieving both volatile and nonvolatile resistive switching in the same material platform is a key milestone towards the development of dense hardware-based neuromorphic computing. We show that, by suitable choice of electrode metals, a single oxide film c ...

American Physical Society (APS)2025

Structural study of nickelate based heterostructures

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Bernat Mundet, Chih-Ying Hsu

Heterostructures consisting of SmNiO3 and NdNiO3 alternating layers with additional LaAlO3 spacer layers were grown and fully characterized by means of x-ray diffraction, atomic force microscopy, and scanning transmission electron microscopy. A change in t ...

Aip Publishing2024

Mapping orthorhombic domains with geometrical phase analysis in rare-earth nickelate heterostructures

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Bernat Mundet

Most perovskite oxides belong to the Pbnm space group, composed of an anisotropic unit cell, A-site antipolar displacements, and oxygen octahedral tilts. Mapping the orientation of the orthorhombic unit cell in epitaxial heterostructures that consist of at ...

Aip Publishing2024

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

Operando insights into correlating CO coverage and Cu-Au alloying with the selectivity of Au NP-decorated Cu2O nanocubes during the electrocatalytic CO2 reduction

Duncan Thomas Lindsay Alexander, Daniele Casari

Electrochemical reduction of CO2 (CO2RR) is an attractive technology to reintegrate the anthropogenic CO2 back into the carbon cycle driven by a suitable catalyst. This study employs highly efficient multi-carbon (C2+) producing Cu2O nanocubes (NCs) decora ...

ROYAL SOC CHEMISTRY2024

Electron-Beam Writing of Atomic-Scale Reconstructions at Oxide Interfaces

Duncan Thomas Lindsay Alexander, Chih-Ying Hsu

The epitaxial growth of complex oxides enables the production of high-quality films, yet substrate choice is restricted to certain symmetry and lattice parameters, thereby limiting the technological applications of epitaxial oxides. In comparison, the deve ...

American Chemical Society (ACS)2024

Role of the coupling of the electronic transitions on the order of the metal-to-insulator phase transition in nickelates

Duncan Thomas Lindsay Alexander

Rare-earth nickelates (chemical formula RNiO3, R being a rare-earth cation) display a temperature-dependent metal-to-insulator transition (MIT) together with a breathing distortion of the NiO6 octahedra units at a temperature ranging from 0 to 600 K depend ...

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

Influence of the sintering atmosphere on the physico-chemical properties and the osteoclastic resorption of β-tricalcium phosphate cylinders

Paul Bowen, Duncan Thomas Lindsay Alexander, Gabrielle Anne Laguisma Sblendorio

One of the most widely used materials for bone graft substitution is β-Tricalcium phosphate (β-TCP;β- Ca3(PO4)2). beta-TCP is typically produced by sintering in air or vacuum. During this process, evaporation of phosphorus ...

Elsevier Sci Ltd2023

Metal-insulator transition in composition-tuned nickel oxide films

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Bernat Mundet

Thin films of the solid solution Nd1-xLaxNiO3 are grown in order to study the expected 0 K phase transitions at a specific composition. We experimentally map out the structural, electronic and magnetic properties as a function of x and a discontinuous, pos ...

IOP Publishing Ltd2023

Electronic Coupling of Metal-to-Insulator Transitions in Nickelate-Based Heterostructures

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Bernat Mundet

In rare earth nickelates, the metal-to-insulator transition observed as a function of temperature can be described using an electronic and a structural order parameter. The electronic one is linked to the electronic disproportionation observed below the tr ...

WILEY2023

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

Investigation of the Impact of Point Defects in InGaN/GaN Quantum Wells with High Dislocation Densities

Jean-François Carlin, Nicolas Grandjean, Raphaël Butté, Duncan Thomas Lindsay Alexander, Pierre Christophe Lottigier, Thomas Fjord Kjaersgaard Weatherley, Davide Maria Di Paola

In this work, we report on the efficiency of single InGaN/GaN quantum wells (QWs) grown on thin (

MDPI2023

Competition between Carrier Injection and Structural Distortions in Electron-Doped Perovskite Nickelate Thin Films

Jean-Marc Triscone, Duncan Thomas Lindsay Alexander, Jonathan Spring, Bernat Mundet

The discovery of superconductivity in doped infinite-layer nickelate thin films has brought increased attention to the behavior of the doped perovskite phase. Despite this interest, the majority of existing studies pertain to hole-doped perovskite rare-ear ...

WILEY2023

Towards an improved understanding of the β-TCP crystal structure by means of “checkerboard” atomistic simulations

Paul Bowen, Duncan Thomas Lindsay Alexander, Gabrielle Anne Laguisma Sblendorio

The large variability of biological responses to beta-TCP implants reported in the literature could possibly be related to subtle differences in the beta-TCP crystal structure. The structure contains one partially occupied site Ca(4). In order to better un ...

2023

Chemically pure beta-tricalcium phosphate powders: Evidence of two crystal structures

Paul Bowen, Duncan Thomas Lindsay Alexander, Gabrielle Anne Laguisma Sblendorio

The question whether beta-tricalcium phosphate (beta-TCP) can form a solid solution with beta-calcium pyrophosphate (beta-CPP) and/or hydroxyapatite (HA) has still not been solved. For this reason, wet-chemically synthesized beta-TCP powders with only 20 p ...

ELSEVIER SCI LTD2021