SIMaP laboratory publishes scientific results in various peer-reviewed international journals. List of those papers and more can be found on the open archive HAL.
Refractory materials are used, among other, in the glass industry, e.g. St Gobain. In this study, we carry out an experimental and modelling dialogue for cohesive zone identification and later prediction for possible cracking in refractory ceramics used in high temperature furnaces, due to thermal gradient. Two scale experimental data (force-displacement curve and DIC) at high temperature DIC (up to 1200°C) on wedge tests are used to calibrate cohesive model parameters. The use of two scale information is shown necessary for reliable identification.
This paper has been selected for the Experimental Mechanics journal cover of volume 60 issue 5.
Fracture and Cohesive Parameter Identification of Refractories by Digital Image Correlation Up to 1200°C
A. Doitrand, R.Estevez, M.Thibault, P.Leplay
Experimental Mechanics 60 (2020) 577-590 (https://doi.org/10.1007/s11340-020-00584-7)
Frequency-tunable toughening in a polymer-metal-ceramic stack using an interfacial molecular nanolayer
M. Kwan, M. Braccini, M. W. Lane, G. Ramanath
Nature Communications, 9(1), 5249. https://doi.org/10.1038/s41467-018-07614-y
The background illustrates the periodic structure of the clathrate, with a unit cell (shown as a white square in the left with a parameter 1 nm. The Ba atoms in red are enclosed in the cages. The coloured curved are the inelastic neutron scattering measurements from which the dispersion reaction and the phonon lifetime has been extracted.
The decaying sinusoidal curve, illustrate the phonon propagation and its time decay (or lifetime) for a phonon wavelength equal to 2 nm.
Direct measurement of individual phonon lifetimes in the clathrate compound Ba7.81Ge40.67Au5.33,
P.-F. Lory, S. Pailhès et al., Nature Communications, 8: 491, 2017, DOI: 10.1038/s41467-017-00584-7
Surprenante contradiction entre faible conductivité thermique des cristaux et longs temps de vie des phonons
published on the Institut National de Physique du CNRS website
While the twisting of individual atomic-scale magnets is set to play a prominent role in future 'spintronics' technologies, the phenomenon was first discussed in detail in the context of 'weak ferromagnets' over half a century ago. It is precisely these materials that now offer a unique opportunity to investigate the effects of changing the magnetic atom type, since this causes almost no change in their structure.
Unfortunately, the direction of the magnetic twists cannot be observed by conventional techniques, since the two twist directions look the same. The researchers overcame this limitation by borrowing ideas from holography and applying them to x-ray 'diffraction', carried out at two of Europe's most powerful x-ray sources: Diamond Light Source in the UK and the European Synchrotron Radiation Source in France. The new technique gave a clear fingerprint of the twist direction, as the magnetic atoms gradually progressed along a row of the periodic table of elements. The results showed a sudden reversal of the twist, between manganese and iron, to the heavier cobalt and nickel atoms. Moreover, the jump is exactly as predicted by theory.
The team are hopeful that their results will bring new insights into an important class of material, and that their technique can be extended to other problems in solid state physics. The success of the computer simulations brings us a small step closer to goal of predicting the properties of technologically-important materials.
Band Filling Control of the Dzyaloshinskii-Moriya Interaction in Weakly Ferromagnetic Insulators, G. Beutier, S. P. Collins, O. V. Dimitrova, V. E. Dmitrienko, M. I. Katsnelson, Y. O. Kvashnin, A. I. Lichtenstein, V. V. Mazurenko, A. G. A. Nisbet, E. N. Ovchinnikova, and D. Pincini, Phys. Rev. Lett. 119, 167201, https://doi.org/10.1103/PhysRevLett.119.167201
We propose here to revisit a classical CVD process with a design of experiment approach to reveal that main parameters influencing the desired properties of an epitaxial layer, here AlN on sapphire, are not necessarily the one you expect. Simple DOE method can bring new insight into a well-established research and can make you go out of your intuition without any increase in experimental cost !
This work is published in Coatings and is enlighten in the front cover of 2017 September issue
Epitaxial Growth of AlN on (0001) Sapphire: Assessment of HVPE Process by a Design of Experiments Approach,
Raphaël Boichot, Danying Chen, Frédéric Mercier, Francis Baillet, Gaël Giusti, Thomas Coughlan, Mikhail Chubarov and Michel Pons, Coatings 2017, 7(9), 136; doi: Coatings 2017, 7(9), 136; doi:10.3390/coatings7090136
Neck curvature, a parameter critical to the understanding of sintering, was determined precisely for the first time for the sintering of a glass powder. This was achieved by studying the microstructure evolution during sintering by high-temperature in-situ nanotomography using an unprecedented combination of fast scan time and high resolution. Those results are gathered in a paper in Materials Today journal and are also the subject of a ESRF' SPOTLIGHT ON SCIENCE.
Fast in situ 3D nanoimaging: a new tool for dynamic characterization in materials science, J. Villanova, R. Daudin, P. Lhuissier, D. Jauffrès, S. Lou, C.L. Martin, S. Labouré, R. Tucoulou, G. Martínez-Criado, L. Salvo, Materials Today (2017); doi: 10.1016/j.mattod.2017.06.0
One way to adjust the properties of a material is by changing its microstructure. This concept is not easily applicable on bulk metallic glasses (BMGs), because they do not consist of grains or different phases and so their microstructure is very homogeneous. One obvious way to integrate inhomogeneities is to produce bulk metallic glass composites (BMGCs). Here we show how to generate BMGCs via high-pressure torsion (HPT) starting from powders (amorphous Zr-MG and crystalline Cu). This approach has been developed in partnership with the Erich Schmid Institute of Materials Science in Leoben, Austria, and demonstrated that by changing the applied shear strains, the refinement of the microstructure is adjustable. The refinement of microstructure increases the hardness and a hardness higher than the initial BMG can be obtained.
From powders to bulk metallic glass composites
Lisa Krämer, Yannick Champion, Rienhard Pipan, Scientific Reports (2017)
Date of update June 18, 2020