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PEOPLE@HES-SO – Annuaire et Répertoire des compétences
PEOPLE@HES-SO – Annuaire et Répertoire des compétences

PEOPLE@HES-SO
Annuaire et Répertoire des compétences

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Burdet Pierre

Burdet Pierre

Maître d'enseignement

Compétences principales

Science des matériaux

Métallurgie appliquée

Optical and Electron Microscopy

Caractérisation mécanique

  • Contact

  • Enseignement

  • Publications

  • Conférences

Contrat principal

Maître d'enseignement

Téléphone: +41 24 557 63 37

Bureau: C59a

Haute école d'Ingénierie et de Gestion du Canton de Vaud
Route de Cheseaux 1, 1400 Yverdon-les-Bains, CH
HEIG-VD
Institut
Institut de conception mécanique et technologie des matériaux (COMATEC)
BSc HES-SO en Microtechniques - Haute école d'Ingénierie et de Gestion du Canton de Vaud
  • Matériaux de l'ingénieur
  • Science des matériaux
  • Laboratoire matériaux
  • Choix des matériaux -Granta
  • Fabrication additive - Techniques d'impression 3D
BSc HES-SO en Systèmes industriels - Haute école d'Ingénierie et de Gestion du Canton de Vaud
  • Choix des matériaux -Granta
  • Fabrication additive - Techniques d'impression 3D

2019

Characterization of local morphology and availability of triple-phase boundaries in solid oxide cell electrodes
Article scientifique ArODES

G. Rinaldi, A. Nakajo, Pierre Burdet, M. Cantoni, W.K.S. Chiu

Acta Materialia,  2019, vol. 178, pp. 194-206

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Résumé:

The performance of solid oxide cells is known to be dependent upon the density of three phase boundaries (TPB), but the potential for improving their effective electrocatalytic activity by morphological adjustments is imprecisely known. A spilling algorithm was developed to characterize the surfaces available for diffusion at TPBs. It scans each slice in a 3-D imaging dataset to measure the interfaces between the solid and the pore phases at each TPB. Because of the stereological approach, these surfaces are defined as “available lengths” (LA). The measurement was tested on artificial packed spheres structures with controlled properties and a percolation theory-based model before application to a real Ni-YSZ. The LA distributions cover 2 orders of magnitude. The subset shorter than the extent of diffusion profiles reported in the literature is in the range of 3% and 20% for Ni and YSZ, respectively, suggesting possible limitations of their effective electrocatalytic properties. The average LA is larger on YSZ than on Ni, which is a trend opposite to the phase diameter. The available length analysis revealed microstructural characteristics that stem from the manufacturing route and cannot be identified by the inspection of standard metric and topological properties. A strong correlation between the available length and the extension of TPB lines is observed for Ni but not for YSZ, despite the predominance of convex shapes, which likely originates from the Ni reduction. This suggests possibilities for controlling the available length by the manufacturing route, depending specifically on the electrocatalytic properties of the phases in composite materials.

2017

One-reactor plasma assisted fabrication of ZnO@TiO 2 multishell nanotubes :
Article scientifique ArODES
assessing the impact of a full coverage on the photovoltaic performance

Alejandro Nicolas Filippin, Manuel Macias-Montero, Zineb Saghi, Pierre Burdet, Juan R. Sanchez-Valencia

Scientific Reports,  2017, vol. 7, article number 9621

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Résumé:

This paper addresses the fabrication of vertically aligned ZnO@TiO2 multishell nanotubes by a combined full vacuum-plasma approach at mild temperatures. The growth is carried out within the premises of a one-reactor approach, i.e. minimizing the number of vacuum chambers and sample transferences. In this way, the interface between ZnO and TiO2 is fully preserved from humidity thus increasing ZnO durability and stability. These nanostructures are studied by scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy in STEM (EDX-STEM). High density one-dimensional arrays of these nanotubes formed on FTO substrates are applied as photoanode in a dye-sensitized solar cell (DSC). The evolution of the dye adsorption capacity and solar cells parameters are explored as a function of the crystallinity and thickness of the TiO2 shell. The results show the critical effect of a full coverage by TiO2 of ZnO core to explain the mixed results found in the literature.

Strontium migration at the GDC-YSZ interface of solid oxide cells in SOFC and SOEC modes
Article scientifique ArODES

G. Rinaldi, A. Nakajo, J. Van Herle, Pierre Burdet, E. Oveisi

ECS Transactions,  2017, vol. 78, no. 1, pp. 3297-3307

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Résumé:

Strontium migration from the oxygen electrode to the interface between the electrolyte and interlayer was investigated in solid oxide cells in fuel cell (SOFC) and electrolysis (SOEC) mode. Four samples were imaged by focused ion beam scanning electron microscopy (FIB-SEM) serial sectioning. After reconstruction, the spatial distribution of the strontium zirconate secondary phase was examined by measuring the volume fractions, phase size distributions, interfacial surface areas and the shape of each detected distinct inclusion. The analysis shows that the accumulation lingers during operation. The results also suggest that the inclusions tend to propagate towards the GDC/YSZ interface. The detrimental effect on the performance was assessed using 3-D finite element transport analysis, by comparing the effective conductivity computed with and without the presence of the secondary phase. The operation in SOFC mode caused a limited decrease of the conductivity, while the effects on the performance are more significant for SOEC operation.

2016

Large-scale ordering of nanoparticles using viscoelastic shear processing
Article scientifique ArODES

Qibin Zhao, Chris E. Finlayson, David R. E. Snoswell, Andrew Haines, Christian Schäfer, Pierre Burdet

Nature Communications,  2016, vol. 7, article number 11661

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Résumé:

Despite the availability of elaborate varieties of nanoparticles, their assembly into regular superstructures and photonic materials remains challenging. Here we show how flexible films of stacked polymer nanoparticles can be directly assembled in a roll-to-roll process using a bending-induced oscillatory shear technique. For sub-micron spherical nanoparticles, this gives elastomeric photonic crystals termed polymer opals showing extremely strong tunable structural colour. With oscillatory strain amplitudes of 300%, crystallization initiates at the wall and develops quickly across the bulk within only five oscillations. The resulting structure of random hexagonal close-packed layers is improved by shearing bidirectionally, alternating between two in-plane directions. Our theoretical framework indicates how the reduction in shear viscosity with increasing order of each layer accounts for these results, even when diffusion is totally absent. This general principle of shear ordering in viscoelastic media opens the way to manufacturable photonic materials, and forms a generic tool for ordering nanoparticles.

Hardness and microstructural variation of Al–Mg–Mn–Sc–Zr alloy
Article scientifique ArODES

Sumiha Ikeshita, Ansis Strodahs, Zineb Saghi, Kazuhiro Yamada, Pierre Burdet

Micron,  2016, vol. 82, pp. 1-8

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Résumé:

Variations of Vickers hardness were observed in Al–Mg–Mn alloy and Al–Mg–Mn–Sc–Zr alloy at different ageing times, ranging from a peak value of 81.2 HV at 54 ks down to 67.4 HV at 360 ks, below the initial hardness value, 71.8 HV at 0 ks for the case of Al–Mg–Mn–Sc–Zr alloy. Microstructures of samples at each ageing stage were examined carefully by transmission electron microscopes (TEMs) both in two-dimensions and three-dimensions. The presence of different types, densities, and sizes of particles were observed dispersed spherical Al3Sc1−xZrx and also block-shaped Al3Sc precipitates growing along <1 0 0>Al with facets {1 0 0} and {1 1 0} of the precipitates. TEM analysis both in two-dimensions and three-dimensions, performed on various samples, confirmed the direct correlation between the hardness and the density of Al3Sc.

2015

Multicomponent signal unmixing from nanoheterostructures :
Article scientifique ArODES
overcoming the traditional challenges of nanoscale X-ray analysis via machine learning

David Rossouw, Pierre Burdet, Francisco de la Peña, Caterina Ducati, Benjamin R. Knappett

Nano Letters,  2015, vol. 15, no. 4, pp. 2716-2720

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Résumé:

The chemical composition of core–shell nanoparticle clusters have been determined through principal component analysis (PCA) and independent component analysis (ICA) of an energy-dispersive X-ray (EDX) spectrum image (SI) acquired in a scanning transmission electron microscope (STEM). The method blindly decomposes the SI into three components, which are found to accurately represent the isolated and unmixed X-ray signals originating from the supporting carbon film, the shell, and the bimetallic core. The composition of the latter is verified by and is in excellent agreement with the separate quantification of bare bimetallic seed nanoparticles.

The dark side of EDX tomography :
Article scientifique ArODES
modeling detector shadowing to aid 3D elemental signal analysis

Catriona S. M. Yeoh, David Rossouw, Zineb Saghi, Pierre Burdet, Rowan K. Leary

Microscopy and Microanalysis,  2015, vol. 21, no. 3, pp. 759–764

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Résumé:

A simple model is proposed to account for the loss of collected X-ray signal by the shadowing of X-ray detectors in the scanning transmission electron microscope. The model is intended to aid the analysis of three-dimensional elemental data sets acquired using energy-dispersive X-ray tomography methods where shadow-free specimen holders are unsuitable or unavailable. The model also provides a useful measure of the detection system geometry.

Enhanced quantification for 3D SEM–EDS :
Article scientifique ArODES
using the full set of available X-ray lines

Pierre Burdet, S. A. Croxall, P. A. Midgley

Ultramicroscopy,  2015, vol. 148, pp. 158-167

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Résumé:

An enhanced method to quantify energy dispersive spectra recorded in 3D with a scanning electron microscope (3D SEM–EDS) has been previously demonstrated. This paper presents an extension of this method using all the available X-ray lines generated by the beam. The extended method benefits from using high energy lines, that are more accurately quantified, and from using soft X-rays that are highly absorbed and thus more surface sensitive. The data used to assess the method are acquired with a dual beam FIB/SEM investigating a multi-element Ni-based superalloy. A high accelerating voltage, needed to excite the highest energy X-ray line, results in two available X-ray lines for several elements. The method shows an improved compositional quantification as well as an improved spatial resolution.

2014

Enhanced quantification for 3D energy dispersive spectrometry :
Article scientifique ArODES
going beyond the limitation of large volume of X-ray emission

Pierre Burdet, Cécile Hébert, Marco Cantoni

Microscopy and Microanalysis,  2014, vol. 20, pp. 1544–1555

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Résumé:

This paper presents a method developed to quantify three-dimensional energy dispersive spectrometry (3D EDS) data with voxel size smaller than the volume from which X-rays are emitted. The influence of the neighboring voxels is corrected by applying recursively a complex quantification, improving thereby the accuracy of the quantification of critically small features. The enhanced quantification method is applied to simulated and measured data. A systematic improvement is obtained compared with classical quantification, proving the concept and the prospect of this method.

2013

Multivariate statistical analysis as a tool for the segmentation of 3D spectral data
Article scientifique ArODES

G. Lucas, Pierre Burdet, M. Cantoni, C. Hébert

Micron,  2013, vol. 52–53, pp. 49-56

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Résumé:

Acquisition of three-dimensional (3D) spectral data is nowadays common using many different microanalytical techniques. In order to proceed to the 3D reconstruction, data processing is necessary not only to deal with noisy acquisitions but also to segment the data in term of chemical composition. In this article, we demonstrate the value of multivariate statistical analysis (MSA) methods for this purpose, allowing fast and reliable results. Using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDX) coupled with a focused ion beam (FIB), a stack of spectrum images have been acquired on a sample produced by laser welding of a nickel–titanium wire and a stainless steel wire presenting a complex microstructure. These data have been analyzed using principal component analysis (PCA) and factor rotations. PCA allows to significantly improve the overall quality of the data, but produces abstract components. Here it is shown that rotated components can be used without prior knowledge of the sample to help the interpretation of the data, obtaining quickly qualitative mappings representative of elements or compounds found in the material. Such abundance maps can then be used to plot scatter diagrams and interactively identify the different domains in presence by defining clusters of voxels having similar compositions. Identified voxels are advantageously overlaid on secondary electron (SE) images with higher resolution in order to refine the segmentation. The 3D reconstruction can then be performed using available commercial softwares on the basis of the provided segmentation. To asses the quality of the segmentation, the results have been compared to an EDX quantification performed on the same data.

Three-dimensional chemical analysis of laser-welded NiTi–stainless steel wires using a dual-beam FIB
Article scientifique ArODES

Pierre Burdet, J. Vannod, A. Hessler-Wyser, M. Rappaz, M. Cantoni

Acta Materialia,  2013, vol. 61, no. 8, pp. 3090-3098

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Résumé:

The biomedical industry has an increasing demand for processes to join dissimilar metals, such as laser welding of NiTi and stainless steel wires. A region of the weld close to the NiTi interface, which previously was shown to be prone to cracking, was further analyzed by energy dispersive spectrometry (EDS) extended in the third dimension using a focused ion beam. As the spatial resolution of EDS analysis is not precise enough to resolve the finest parts of the microstructure, a new segmentation method that uses in addition secondary-electron images of higher spatial resolution was developed. Applying these tools, it is shown that this region of the weld close to the NiTi interface does not comprise a homogeneous intermetallic layer, but is rather constituted by a succession of different intermetallics, the composition of which can be directly correlated with the solidification path in the ternary Fe–Ni–Ti Gibbs simplex.

2011

Study of the twinned dendrite tip shape II :
Article scientifique ArODES
experimental assessment

M. A. Salgado-Ordorica, Pierre Burdet, M. Cantoni, M. Rappaz

Acta Materialia,  2011, vol. 59, no. 13, pp. 5085-5091

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Résumé:

The favorable growth kinetics of twinned dendrites can be explained by their complex morphology, multiple side branching mechanisms, growth undercooling and tip morphology. Three models were proposed for the twinned dendrite tip shape: (i) a grooved tip [1] satisfying the Smith condition at the triple line; (ii) a doublon [2], i.e. a double-tip dendrite that grows with a narrow and deep liquid channel in its center; and (iii) a pointed (or edgy) tip [3], with consideration of the solid–liquid interfacial energy anisotropy. In the first part of this work, phase field simulations of half a twinned dendrite with an appropriate boundary condition to reproduce the Smith condition supported the doublon conjecture, with a narrow liquid channel ending its solidification with the formation of small liquid droplets. In this part, experimental observations of twinned dendrite tips reveal the presence of a small, but well-defined, groove, thus definitely eliminating the edged tip hypothesis. Focused ion beam nanotomography and energy-dispersive spectroscopy chemical analysis in a transmission electron microscope reveal the existence of a positive solute gradient in a region localized within 2 μm around the twin plane. In Al–Zn specimens, small particles aligned within the twin plane further support the doublon conjecture and the predicted formation of small liquid droplets below the doublon root.

2009

Dexamethasone-containing biodegradable superparamagnetic microparticles for intra-articular administration :
Article scientifique ArODES
physicochemical and magnetic properties, in vitro and in vivo drug release

Nicoleta Butoescu, Olivier Jordan, Pierre Burdet, Pierre Stadelmann, Alke Petri-Fink

European Journal of Pharmaceutics and Biopharmaceutics,  2009, vol. 72, no. 3, pp. 529-538

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Résumé:

Compared with traditional drug solutions or suspensions, polymeric microparticles represent a valuable means to achieve controlled and prolonged drug delivery into joints, but still suffer from the drawback of limited retention duration in the articular cavity. In this study, our aim was to prepare and characterize magnetic biodegradable microparticles containing dexamethasone acetate (DXM) for intra-articular administration. The superparamagnetic properties, which result from the encapsulation of superparamagnetic iron oxide nanoparticles (SPIONs), allow for microparticle retention with an external magnetic field, thus possibly reducing their clearance from the joint. Two molecular weights of poly(lactic-co-glycolic acid) (PLGA) were used, 12 and 19 kDa. The prepared batches were similar in size (around 10 μm), inner morphology, surface morphology, charge (neutral) and superparamagnetic behaviour. The SPION distribution in the microparticles assessed by TEM indicates a homogeneous distribution and the absence of aggregation, an important factor for preserving superparamagnetic properties. DXM release profiles were shown to be quite similar in vitro (ca. 6 days) and in vivo, using a mouse dorsal air pouch model (ca. 5 days).

2017

Electron microscopy (big and small) data analysis with the open source software package HyperSpy
Conférence ArODES

Francisco de la Peña, Tomas Ostasevicius, Vidar Tonaas Fauske, Pierre Burdet, Petras Jokubauskas

Proceedings of the Microscopy Microanalysis 2017 Meeting

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2016

Post-test analysis on a solid oxide cell stack operated for 10,700 hours in steam electrolysis mode
Conférence ArODES

G. Rinaldi, S. Diethelm, E. Oveisi, Pierre Burdet, J. Van Herle

Proceedings of the 12th EUROPEAN SOFC SOE FORUM

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Résumé:

A solid oxide short stack composed of 6 Ni-YSZ supported cells, YSZ electrolyte and GDC-LSC oxygen electrode has been tested for 10,700 hours in steam electrolysis. Initial degradation was followed by a global stabilization of the performance after lowering the current density, with a degradation rate below 0.5% kh−1. Post-test analysis has been conducted on two repeating units (RUs) to highlight the most significant microstructure alterations. Nickel depletion was observed in the hydrogen electrode close to the interface with the electrolyte. Formation of small pores in the electrolyte was detected along the grain boundaries. A consequent detachment related to this phenomenon was observed in proximity of the GDC compatibility layer. At the oxygen electrode side, the formation of a ∼1 µm dense mixed layer of GDC and YSZ was observed. Strontium from the LSC electrode migrated through GDC pores and reacted with YSZ, forming evident SrZrO3 inclusions. Distinct accumulation of silicon at the Ni/YSZ interface and chromium on the GDC barrier layer have been observed in both RUs. Despite this range of alterations observed, the stack degradation remained limited, testified from the fact that performance decay between 4,000 and 10,000 hours of operation was virtually nil.

2008

Magnetic-field induced strains in ferromagnetic shape memory alloy Ni55Mn23Ga22 deposited by RF-magnetron sputtering
Conférence ArODES

Florent Bernard, Christophe Rousselot, Patrick Delobelle, Laurent Hirsinger, Pierre Burdet

Proceedings of the Eleventh International Conference on Plasma Surface Engineering

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Résumé:

1.5 µm–Ni55Mn23Ga22 ferromagnetic thin films were deposited onto silicon substrates and silicon single beam cantilever using radio-frequency magnetron sputtering. As-deposited sample and heat-treated thin films were studied on their silicon substrates and peeled off to determine the influence of the stress. Post-heat treatment process allows at the films to achieve the shape memory effect (SME). Vibrating sample magnetometer (VSM) and deflection measurement of the sample annealed at 873 K during 36 ks exhibit ferromagnetic martensitic structure with a typical SME response to the magnetic field induced strains which match the values of the bulk material.

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