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196 results on '"Casanove, M. -J"'

54. Magnetic properties of CoNRhMnanoparticles: experiment and theory

Author

Muñoz-Navia, M., primary, Dorantes-Dávila, J., additional, Zitoun, D., additional, Amiens, C., additional, Chaudret, B., additional, Casanove, M.-J., additional, Lecante, P., additional, Jaouen, N., additional, Rogalev, A., additional, Respaud, M., additional, and Pastor, G. M., additional

Published
2008
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88. Synthesis and Magnetic Properties of Nickel Nanorods

Author

Cordente, N., Respaud, M., Senocq, F., Casanove, M.-J., Amiens, C., and Chaudret, B.

Abstract

Nickel nanoparticles of tunable shape have been synthesized in THF, in the presence of hexadecylamine (HDA) or trioctylphosphineoxide (TOPO), in mild conditions and characterized by HREM and SQUID measurements. The formation of nanorods is promoted by a high amine content in the reaction medium. In contrast to what is observed for TOPO-protected nickel particles, the saturation magnetization of HDA-capped nanoparticles is comparable to that of bulk nickel, which demonstrates that the coordination of an amine ligand does not alter the magnetic properties of nickel.

Published
2001

91. Nanoscale Bimetallic Co<INF>x</INF><INF></INF>Pt<INF>1</INF><INF>-</INF><INF>x</INF><INF></INF> Particles Dispersed in Poly(vinylpyrrolidone): Synthesis from Organometallic Precursors and Characterization

Author

Ely, T. O., Pan, C., Amiens, C., Chaudret, B., Dassenoy, F., Lecante, P., Casanove, M.-J., Mosset, A., Respaud, M., and Broto, J.-M.

Abstract

The reaction of Co(η3-C8H13)(η4-C8H12) and Pt2(dba)3 (dba = bis-dibenzylidene acetone) under dihydrogen leads in the presence of poly(vinylpyrrolidone) to nanometric bimetallic particles CoxPt1-x. The composition of the material is determined by the initial ratio of the two organometallic precursors. The bimetallic character of the particles is evidenced by magnetic, structural, and spectroscopic studies. Structural changes are evidenced both by HREM and WAXS:  platinum rich particles adopt a fcc crystalline structure while cobalt rich particles adopt a non periodic polytetraedral arrangement. The magnetic properties of the materials have been investigated. ZFC/FC measurements show that the particles are superparamagnetic and that their size dispersity is very low. From isothermal magnetization measurements, the extrapolated value of the coercive field HC (T = 0) is shown to increase continuously with Pt concentration, which is characteristic of bimetallic particles.

Published
2000

92. Misfit relaxation of La0.7Sr0.3MnO3 thin films by a nanodot segregation mechanism.

Author

Abellán, P., Moreno, C., Sandiumenge, F., Obradors, X., and Casanove, M.-J.

Subjects
MAGNETIC properties of thin films, LANTHANUM compounds, NANOCOMPOSITE materials, MOLECULAR self-assembly, NANOSTRUCTURES, STRAINS & stresses (Mechanics), RELAXATION phenomena, MAGNETORESISTANCE, THICKNESS measurement
Abstract

Partially segregated La0.7Sr0.3MnO3 (LSMO) nanocomposite films are shown to exhibit a thickness dependent self-assembled structure. The morphological evolution of the nanocomposite and the misfit strain of the LSMO phase are linked through the topological distribution of La-Sr oxide nanodots within the film. Misfit relaxation occurs above a critical thickness, hc, coinciding with the nucleation of La-Sr oxide nanodots at the film-substrate interface. Below hc, the same dots outcrop the film surface, forming islands. As a consequence of this misfit relaxation mechanism, an enhancement in the magnetoresistance with increasing thickness is measured. [ABSTRACT FROM AUTHOR]

Published
2011
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93. A New Synthetic Method toward Bimetallic Ruthenium Platinum Nanoparticles; Composition Induced Structural Changes

Author

Pan, C., Dassenoy, F., Philippot, K., Amiens, C., Lecante, P., Mosset, A., Casanove, M.-J., and Chaudret, B.

Abstract

The reaction of Pt(dba)2 with Ru(COD)(COT) in various proportions under dihydrogen in the presence of PVP leads to the formation of bimetallic nanoparticles of definite compositions resulting from the relative concentration of the two complexes in the initial solution. The progressive incorporation of ruthenium into the platinum matrix leads to structural changes from face-centered cubic (fcc) for high platinum contents to hexagonal close-packed (hcp) for high ruthenium contents. For the composition Pt1Ru3 a contraction of the size of the particles (ca. 1.1 nm) and of the size distribution indicates the presence of a new phase consisting of monodisperse particles for which a model of truncated twinned octahedrons of 79 atoms was proposed.

Published
1999

97. Resolution and robustness in image processing: a new regularization principle

Author

Lannes, A., Casanove, M. J., and Roques, S.

Abstract

As band-limited interpolation is possible to some extent, whereas band-limited extrapolation is strictly forbidden, it is natural to state the deconvolution problem in terms of weighted interpolation (in the frequency domain). The corresponding regularization principle, which is to be compared with that of Tikhonov, proves to be intimately related to the notion of resolution: the aperture to be synthesized explicitly appears in the definition of the stabilizing component of the objective function. The choice of this synthetic aperture of course depends on the error analysis. The study developed in this paper shows, in particular, how the amount and the nature of the interpolation to be performed play a central part in the error propagation. The corresponding analytic parameters are exhibited. This survey, which is illustrated with the aid of a simulated example, also indicates how to estimate the degree of confidence of any other deconvolution technique (clean, filtered singular-value decomposition, maximum-entropy, etc.).

Published
1987

99. Ferroelastic behaviour of the (Ln)Ba2Cu3O6 x orthorhombic phase

Author

Snoeck, E., Casanove, M. J., Baules, P., and Roucau, C.

Abstract

The orthorhombic phase of the high Tc superconductor (Ln)Ba2Cu3O6+A is observed in transmission electron microscopy. This phase is ferroelastic and exhibits two different orientation domains. A full description of the twin boundaries is given. The behaviour of the ferroelastic domains at the intersection of orthogonal twin walls is more particularly investigated.

Published
1989
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100. Transmission electron microscopy and high-resolution electron microscopy of growth defects in La2-xSrxCuO4thin films

Author

Alimoussa, A., Casanove, M.-J., and Hutchison, J.L.

Abstract

AbstractPlanar defects extending through the whole film thickness have been observed by transmission electron microscopy in La2-xSrxCuO4(x= 0·15) thin films. Electron diffraction experiments on plan-view specimens showed that the defects were located in (101) or (011)-type planes. The defects have been analysed by high-resolution lattice imaging and their displacement vector determined using image processing. Possible origins for these kinds of defect are discussed and comparison is made with pure shear defects due to nonstoichiometry. Evidence for the presence of such pure shear defects, having a displacement vector R= 1/6[031], was indeed also given by the experiments. Models for the different kinds of defect have been developed.

Published
1997
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