CNRS Materials and Physical Engineering Laboratory

Grenoble, France

CNRS Materials and Physical Engineering Laboratory

Grenoble, France

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Ouisse T.,CNRS Materials and Physical Engineering Laboratory | Chaussende D.,CNRS Materials and Physical Engineering Laboratory
Physical Review B - Condensed Matter and Materials Physics | Year: 2012

We show that some important features characterizing the M n +1AX n phases, a family of hexagonal-structure ternary carbides and nitrides (X) including a transition metal (M) and an A-group element (A), can be reproduced by modifying the spin model known as the axial next-nearest-neighbor Ising model into a form where pseudospin inversion changes the system energy and requires the inclusion of single- and three-spin products. We describe the various MAX phases in terms of M-A or M-X bilayer stacking along the c axis. We discuss the dependence of the cohesive energy and phase stability on coupling parameters which characterize the first- and second-neighbor interactions between those bilayers. We also address the case of "hybrid" MAX phases. © 2012 American Physical Society.


Crouzier T.,CNRS Materials and Physical Engineering Laboratory | Boudou T.,CNRS Materials and Physical Engineering Laboratory | Picart C.,CNRS Materials and Physical Engineering Laboratory
Current Opinion in Colloid and Interface Science | Year: 2010

In recent years, the layer-by-layer technique has grown in various fields. One of the emerging trends of bio-applications is the use of polysaccharides as main film components, which stems from their intrinsic physical, chemical and biological properties. These allow the simple formation, by self-assembly, of new kinds of mimics of extra-cellular matrices from plant and animal tissues. These assemblies, which possess specific properties arising from their hydration and internal composition, can indeed contain additional functionalities obtained by chemical modification of the biopolymers or film post-processing. They can be molded into different forms (films, membranes, and capsules). © 2010 Elsevier Ltd.


Boudou T.,CNRS Materials and Physical Engineering Laboratory | Crouzier T.,Montpellier University | Ren K.,CNRS Materials and Physical Engineering Laboratory | Blin G.,Montpellier University | And 2 more authors.
Advanced Materials | Year: 2010

The design of advanced functional materials with nanometer- and micrometer-scale control over their properties is of considerable interest for both fundamental and applied studies because of the many potential applications for these materials in the fields of biomedical materials, tissue engineering, and regenerative medicine. The layer-by-layer deposition technique introduced in the early 1990s by Decher, Moehwald, and Lvov is a versatile technique, which has attracted an increasing number of researchers in recent years due to its wide range of advantages for biomedical applications: ease of preparation under "mild" conditions compatible with physiological media, capability of incorporating bioactive molecules, extracellular matrix components and biopolymers in the films, tunable mechanical properties, and spatio-temporal control over film organization. The last few years have seen a significant increase in reports exploring the possibilities offered by diffusing molecules into films to control their internal structures or design "reservoirs" , as well as control their mechanical properties. Such properties, associated with the chemical properties of films, are particularly important for designing biomedical devices that contain bioactive molecules. In this review, we highlight recent work on designing and controlling film properties at the nanometer and micrometer scales with a view to developing new biomaterial coatings, tissue engineered constructs that could mimic in vivo cellular microenvironments, and stem cell "niches". © 2010 WILEY-VCH Vorlag GmbH & Co. KGaA.


Besson R.,CNRS Materials and Physical Engineering Laboratory
Acta Materialia | Year: 2010

The aim of this work is to give the independent-point-defect thermodynamics of ordered compounds a sufficiently general flavour, adapted to and working for multicomponent alloys. Generalizing previous approaches, we first show that an appropriate description for a crystal with point defects allows treatment of the practically important pressure and defect volume parameters in the grand canonical framework, the equivalence of which is explicited with the closer to experiments isothermal-isobaric conditions. Since industrial applications often involve multialloyed compounds, we then derive an operational tool for atomic-scale investigations of long-range order alloys with complex crystallographies and multiple additions. © 2009 Acta Materialia Inc.


Thuinet L.,CNRS Materials and Physical Engineering Laboratory | Legris A.,CNRS Materials and Physical Engineering Laboratory
Acta Materialia | Year: 2010

The influence of a crystallographic symmetry break on the morphology of precipitates during the coherent precipitation of a trigonal phase in a close-packed hexagonal matrix is analyzed. It is pointed out that in spite of the isotropy of the stress-free strain of the precipitate in the basal plane, the existence of an extra elastic constant in the precipitate (associated to the loss of symmetry) induces a morphological evolution from a shape having a symmetry of revolution around the threefold axis to a needle-like one oriented along the compact directions in the basal plane. These general considerations are applied to the case of zirconium hydrides, the crystallography of which has recently been identified to be coherent with that of the αZr matrix. © 2009 Acta Materialia Inc.


Mercier F.,CNRS Materials and Physical Engineering Laboratory | Chaix-Pluchery O.,CNRS Materials and Physical Engineering Laboratory | Ouisse T.,CNRS Materials and Physical Engineering Laboratory | Chaussende D.,CNRS Materials and Physical Engineering Laboratory
Applied Physics Letters | Year: 2011

The lack of single crystalline Ti3SiC2 samples is currently limiting the accurate measurement of its basic properties as its layered crystalline structure presents a very strong anisotropy. In this letter, we report the growth of pure Ti3SiC2 single crystals after a careful study of the Ti3SiC2 liquidus surface extent through thermodynamical calculations. From a Raman scattering study on those single crystals, an unambiguous assignment of most of the phonon modes has been established, giving an answer to the discrepancies existing in the literature. © 2011 American Institute of Physics.


Mercier F.,CNRS Materials and Physical Engineering Laboratory | Ouisse T.,CNRS Materials and Physical Engineering Laboratory | Chaussende D.,CNRS Materials and Physical Engineering Laboratory
Physical Review B - Condensed Matter and Materials Physics | Year: 2011

Atomic step edges can exhibit a morphological instability under step-flow conditions (the so-called Bales-Zangwill instability). Such instabilities are ascribed to the fact that adatoms approaching a step from opposite directions do not see the same energy barrier to step incorporation (Ehrlich-Schwoebel or ES effect). Due to the very low solubility of carbon in the melt, Ti 3SiC2 grown from a Ti-Si liquid phase is an experimental example of two-dimensional (2D) growth. In addition, the ratio between the incorporation rates at a step from the lower terrace and from the upper terrace is probably very high. The latter particularity makes the steps lying below a terrace including an unstable step independent from the forming instability, so that an instability front may appear just on one terrace, whereas the neighboring steps remain stable. Besides, foreign-particle-assisted growth can result in the production of extremely elongated islands or peninsulas on a given terrace, which then form very long grooves between the island edge and the upper terrace step. This provides the ability to test the respective stability of lines and grooves on a single terrace, and to verify that shrinking grooves are more stable than simple steps, as recently demonstrated by another author. © 2011 American Physical Society.


Chaix-Pluchery O.,CNRS Materials and Physical Engineering Laboratory | Kreisel J.,CNRS Materials and Physical Engineering Laboratory
Phase Transitions | Year: 2011

We report an investigation of perovskite-type SmScO3 and NdScO3 single crystals by Raman scattering in various scattering configurations and at different wavelengths. The reported Raman spectra, together with the phonon mode assignment, set the basis for the use of Raman scattering for the structural investigation of rare earth (RE) scandates. Further to the phonon signature, a fluorescence signal is observed for both scandates and is particularly intense for NdScO3 when using a 488 or 514 nm excitation line. A comparison of Raman spectra of RE-scandates with literature Raman data on orthorhombic perovskites shows that the frequency of particular modes scales with the orthorhombic distortion in terms of the rotation (or tilt) angle of the ScO6 octahedra. © 2011 Taylor and Francis.


Roland T.,CNRS Materials and Physical Engineering Laboratory
Materials Science Forum | Year: 2010

The field of application of composites is ever-growing because of their unrivalled combinations of functional and structural properties. Such associations seem the more improvable as there are at once manifold possibilities to modify the architecture of composites, their route of elaboration, an ever-increasing scientific potency for both experimental investigations and modelling, and always more demanding materials performances in projects. This presentation wants to illustrate all these aspects by the example of metal matrix composites (MMCs) mostly elaborated by severe plastic deformation. Emphasis is given to results dealing with the effects of composite design and conditions of metalworking on the success of the fabrication process that depends on the uniformity of deformation and/or on the quality of the interfaces. At last, the consequences of all these data, and the need of complementary work, for the continuous improvement of the properties MMCs are delineated. © (2010) Trans Tech Publications.


Ouisse T.,CNRS Materials and Physical Engineering Laboratory | Chaussende D.,CNRS Materials and Physical Engineering Laboratory | Auvray L.,CNRS Materials and Physical Engineering Laboratory
Journal of Applied Crystallography | Year: 2010

The micropipe-induced birefringence of 6H silicon carbide (SiC) is measured and quantitatively modelled. A good agreement can be obtained between theory and experiment, provided that background residual stress is added to the local dislocation-induced stress. Observations are compatible with or predictable from the Burgers vector values, and birefringence is shown to be an interesting tool for probing the nature of the dislocations associated with e.g. micropipes; it is also faster than and complementary to the more involved techniques of transmission electron microscopy or X-ray topography. © 2010 International Union of Crystallography Printed in Singapore-all rights reserved.

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