Search

Your search keyword '"Chaudret, B."' showing total 328 results
Start Over Author "Chaudret, B." Language english
328 results on '"Chaudret, B."'

1. Iron wool as a heating agent for magnetic catalysis: Experiments and analysis of heating properties under a high-frequency magnetic field.

Author

Daccache, S., Ghosh, S., Marias, F., Chaudret, B., and Carrey, J.

Subjects
EDDY current losses, HETEROGENEOUS catalysis, MAGNETIC materials, HYSTERESIS loop, MAGNETIC fields, WOOL
Abstract

Magnetically induced heterogeneous catalysis has been attracting attention due to its high energy efficiency and flexibility for dynamic reactor control. Iron wool is a commercial, low-cost, and versatile heating agent, which has been used in several magnetic catalysis studies, but its heating properties have never been investigated. Here, the properties of three types of Fe wool were studied using optical and electronic microscopy, x-ray diffraction, and measurements of both heating power and high-frequency hysteresis loops. The effects of strand width, packing, and magnetic field amplitude and frequency were studied. A maximum specific absorption rate (SAR) around 700 W/g under a rms field of 47.4 mT at 93 kHz was measured for the larger width Fe wool. High-frequency hysteresis loops were used to quantify the contribution of hysteresis losses and eddy currents to total heating. Eddy currents contribute 65%–90% to the global heating depending on the strand width. Coating the wool with SiO2 and Ni has negative effects on the SAR but none on hysteresis losses. It is interpreted as originating from the cut-off of inter-wire eddy currents due to the insulating (SiO2, oxidized Ni) nature of the coating. Last, it was found that adding more Fe wool in a given volume mostly decreases the SAR. This effect could be not only due to the absorption and/or screening of the field by surface strands but also due to magnetic interactions. The results described in this work give insights into the magnetic heating of microscale magnetic materials and optimize their use for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]

Published
2024
Full Text
View/download PDF

5. Unraveling the role of zinc complexes on indium phosphide nanocrystal chemistry.

Author

McVey, B. F. P., Swain, R. A., Lagarde, D., Tison, Y., Martinez, H., Chaudret, B., Nayral, C., and Delpech, F.

Subjects
INDIUM phosphide, ZINC, SURFACE passivation, CHEMISTRY, OPTICAL properties
Abstract

The addition of zinc complexes to the syntheses of indium phosphide nanocrystals (InP NCs) has become commonplace, due to their ability to alter and significantly improve observed optical properties. In this paper, the role of zinc complexes on the synthesis and observed properties of InP is carefully examined. Produced InP and InP:Zn2+ NCs are thoroughly characterized from both structural (core and surface) and optical perspectives over a wide range of Zn2+ compositions (0%–43% atomic content). We find no differences in the physical (NC size and polydispersity) and structural properties (crystallographic phase) of InP and InP:Zn2+ NCs. Optically, significant changes are observed when zinc is added to InP syntheses, including blueshifted absorption edges and maxima, increased quantum yields, and the near elimination of surface state emission. These improved optical properties result from surface passivation by zinc carboxylate moieties. Changes to the optical properties begin at zinc concentrations as low as 5%, demonstrating the high sensitivity of InP optical properties to exogenous species. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

11. CHAPTER 5. Gases

Author

Yi, D., Chaudret, B., Soulantika, Aikaterini, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Fédération de recherche « Matière et interactions » (FeRMI), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), and Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC)

Subjects
[CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2021
Full Text
View/download PDF

12. X-Ray magnetic circular dichroism studies of FeRh nanoparticles

Author

Smekhova, A., Ciuculescu, D., Lecante, P., Wilhelm, F., Amiens, C., Rogalev, A., and Chaudret, B.

Subjects
Magnetic moment -- Analysis, Nanoparticles -- Analysis, Business, Electronics, Electronics and electrical industries
Abstract

[Fe.sub.x][Rh.sub.100-x] (x = 50, 80) nanoparticles (NPs) with an average diameter of ~2 nm were prepared by simultaneous decomposition of stoichiometric quantities of Fe[[N[(Si[([CH.sub.3]).sub.3]).sub.2])].sub.2] and Rh[([C.sub.3][H.sub.5]).sub.3] using two different routes: 1) a standard hydrogenation procedure and 2) a new one based on use of amino-borane as a reducing agent. All samples were found to be superparamagnetic with a blocking temperature below 10 K. Results of X-Ray magnetic circular dichroism (XMCD) experiments at the Fe K-edge and the Rh [L.sub.2,3] edges have shown that not only iron but also rhodium atoms are magnetic as a result of hybridization of Fe 3d states with 4d states of Rh. The total induced magnetic moment of Rh atoms as well as its spin and orbital contributions are shown to depend on chemical composition of [NP.sub.S] and the preparation method. Index Terms--Induced magnetic moment, magnetic nanoparticles, X-ray magnetic circular dichroism.

Published
2008

15. Chemisorption on nickel nanoparticles of various shapes: lnfluence on magnetism

Author

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

Subjects
Ligands -- Magnetic properties, Organometallic chemistry -- Research, Nickel -- Magnetic properties, Physics
Abstract

Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)(sub 2) (COD=cycloocta-1, 5-diene), with dihydrogen, in the presence of various stabilizing agents. This stabilizing agent was selected for the production of nickel anorods, and the influence of ligands on the effective anisotropy is discussed.

Published
2003

16. Synthesis and magnetism of CoxRh(sub 1-x) and CoxRu(sub 1-x) nanoparticles

Author

Zitoun, D., Amiens, C., Chaudret, B., Fromen, M.-C., Lecante, P., Casanove, M.-J., and Respaud, M.

Subjects
Ruthenium -- Research, Ruthenium -- Magnetic properties, Chemistry, Physical and theoretical -- Research, Chemicals, plastics and rubber industries
Abstract

The synthesis of CoxRh(sub 1-x) and CoxRu(sub 1-x) alloys of nanometric size dispersed in a polymer matrix through the simultaneous decomposition of the organometallic precursors in solution in mild conditions is described. These structural studies enable to find some analogies between three CoM systems (M= Ru, Rh, Pt).

Published
2003

18. Zwitterionic amidinates as effective ligands for platinum nanoparticle hydrogenation catalysts† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c6sc05551f Click here for additional data file

Author

Martínez-Prieto, L. M., Cano, I., Márquez, A., Baquero, E. A., Tricard, S., Cusinato, L., del Rosal, I., Poteau, R., Coppel, Y., Philippot, K., Chaudret, B., Cámpora, J., and van Leeuwen, P. W. N. M.

Subjects
Chemistry
Abstract

Pt NPs covered with zwitterionic amidinates as ligands exhibit an exciting ligand effect in the hydrogenation of carbonyl groups when electron donor/acceptor groups are introduced in the N-substituents., Ligand control of metal nanoparticles (MNPs) is rapidly gaining importance as ligands can stabilize the MNPs and regulate their catalytic properties. Herein we report the first example of Pt NPs ligated by imidazolium-amidinate ligands that bind strongly through the amidinate anion to the platinum surface atoms. The binding was established by 15N NMR spectroscopy, a precedent for nitrogen ligands on MNPs, and XPS. Both monodentate and bidentate coordination modes were found. DFT showed a high bonding energy of up to –48 kcal mol–1 for bidentate bonding to two adjacent metal atoms, which decreased to –28 ± 4 kcal mol–1 for monodentate bonding in the absence of impediments by other ligands. While the surface is densely covered with ligands, both IR and 13C MAS NMR spectra proved the adsorption of CO on the surface and thus the availability of sites for catalysis. A particle size dependent Knight shift was observed in the 13C MAS NMR spectra for the atoms that coordinate to the surface, but for small particles, ∼1.2 nm, it almost vanished, as theory for MNPs predicts; this had not been experimentally verified before. The Pt NPs were found to be catalysts for the hydrogenation of ketones and a notable ligand effect was observed in the hydrogenation of electron-poor carbonyl groups. The catalytic activity is influenced by remote electron donor/acceptor groups introduced in the aryl-N-substituents of the amidinates; p-anisyl groups on the ligand gave catalysts several times faster the ligand containing p-chlorophenyl groups.

Published
2017

26. Reactivity and structural evolution of urchin-like Co nanostructures under controlled environments

Author

Soulantika, Aikaterini, Dembele, K., Moldovan, S., Hirlimann, Ch., Harmel, J., SOULANTICA, K., Serp, P., Chaudret, B., Gay, A.-S., Maury, S., Berliet, A., FECANT, A., Ersen, O., Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Institut de Chimie de Toulouse (ICT-FR 2599), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UPS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UPS), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UPS), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), Institut de Physique et Chimie des Matériaux de Strasbourg (IPCMS), Université de Strasbourg (UNISTRA)-Centre National de la Recherche Scientifique (CNRS)-Matériaux et nanosciences d'Alsace, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Réseau nanophotonique et optique, Université de Strasbourg (UNISTRA)-Université de Haute-Alsace (UHA) Mulhouse - Colmar (Université de Haute-Alsace (UHA))-Centre National de la Recherche Scientifique (CNRS)-Université de Strasbourg (UNISTRA), IPCMS, Université Strasbourg-CNRS, Laboratoire de chimie de coordination (LCC), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Université Toulouse III - Paul Sabatier (UPS), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Université Fédérale Toulouse Midi-Pyrénées-Institut de Recherche pour le Développement (IRD)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Plasticité, Endommagement et Corrosion des Matériaux (PECM-ENSMSE), École des Mines de Saint-Étienne (Mines Saint-Étienne MSE), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-SMS-Centre National de la Recherche Scientifique (CNRS), IFP Energies nouvelles (IFPEN), and Université Louis Pasteur - Strasbourg I-Centre National de la Recherche Scientifique (CNRS)

Subjects
[CHIM.MATE]Chemical Sciences/Material chemistry, ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2018
Full Text
View/download PDF

30. Probing dynamics of nanoparticle chains formation during magnetic hyperthermia using time-dependent high-frequency hysteresis loops.

Author

Mille, N., De Masi, D., Faure, S., Asensio, J. M., Chaudret, B., and Carrey, J.

Subjects
HYSTERESIS loop, MAGNETIC fields, FEVER, MAGNETIC nanoparticles, TRANSCRANIAL magnetic stimulation, TIME measurements, HEAT stroke, FOOD chains
Abstract

The heating power of magnetic nanoparticles (MNPs) submitted to high-frequency magnetic fields is generally probed using calorimetric methods, which suppose that the heating power does not evolve with time. Among the several parameters governing MNP heating properties, their organization into chains under the influence of the applied magnetic field is of key importance, though the dynamic of this phenomenon has been rarely studied experimentally. In the present article, time-resolved high-frequency hysteresis loops are used to probe the dynamics of chain formation on a sample of 17.3 ± 2.2 nm FeNi3 MNPs. Chains are formed on a timescale, which strongly depends on the magnetic field amplitude, ranging from several tens of seconds to less than 100 ms, but does not depend on frequency in the range studied here (from 9 to 78 kHz). Both the heating power and hysteresis loop squareness increase with time as chains progressively form. These findings have important methodological consequences when defining protocols or analyzing data issued from calorimetric measurements since, in samples where chains form, the heating power varies on a time scale that can be comparable to typical measurement times. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

31. A setup to measure the temperature-dependent heating power of magnetically heated nanoparticles up to high temperature.

Author

Mille, N., Faure, S., Estrader, M., Yi, D., Marbaix, J., De Masi, D., Soulantica, K., Millán, A., Chaudret, B., and Carrey, J.

Subjects
HIGH temperatures, COOLING curves, NANOPARTICLES, CHEMICAL reactions, MAGNETIC fields
Abstract

Magnetic heating, namely, the use of heat released by magnetic nanoparticles (MNPs) excited with a high-frequency magnetic field, has so far been mainly used for biological applications. More recently, it has been shown that this heat can be used to catalyze chemical reactions, some of them occurring at temperatures up to 700 °C. The full exploitation of MNP heating properties requires the knowledge of the temperature dependence of their heating power up to high temperatures. Here, a setup to perform such measurements is described based on the use of a pyrometer for high-temperature measurements and on a protocol based on the acquisition of cooling curves, which allows us to take into account calorimeter losses. We demonstrate that the setup permits to perform measurements under a controlled atmosphere on solid state samples up to 550 °C. It should in principle be able to perform measurements up to 900 °C. The method, uncertainties, and possible artifacts are described and analyzed in detail. The influence on losses of putting under vacuum different parts of the calorimeter is measured. To illustrate the setup possibilities, the temperature dependence of heating power is measured on four samples displaying very different behaviors. Their heating power increases or decreases with temperature, displaying temperature sensibilities ranging from −2.5 to +4.4% K−1. This setup is useful to characterize the MNPs for magnetically heated catalysis applications and to produce data that will be used to test models permitting to predict the temperature dependence of MNP heating power. [ABSTRACT FROM AUTHOR]

Published
2021
Full Text
View/download PDF

33. NHC-stabilised Rh nanoparticles: Surface study and application in the catalytic hydrogenation of aromatic substrates

Author

Blondeau, P., Martinez-Espinar, F., Nolis, P., Chaudret, B., Claver, C., Castillón, S., Godard, C., Departament de Quimica Fisica i Inorganica, Universitat Rovira i Virgili, Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Departament de Quimica Analitica i Quimica Organica, Servei de Ressonància Magnètica Nuclear, Facultat de Ciències, Universitat Autònoma de Barcelona, Universitat Autònoma de Barcelona (UAB), Centre Tecnològic de Química, Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie de Toulouse (ICT-FR 2599), Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Institut de Chimie du CNRS (INC)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD)-Institut de Chimie du CNRS (INC), Síntesis Orgànica Estereoselectiva, Organometàl.lics i Catàlisi Homogènia, Grup de Quimiometria, Qualimetria i Nanosensors, Química Física i Inorgànica, and Química Analítica i Química Orgànica

Subjects
rhodium nanoparticles, Phenol, NHC, NHCs, Pyridine, Quinoline, Química, 0021-9517, Surface, Chemistry, Aromatic ketone, Rodi, Nanoparticles, Rhodium, [CHIM.COOR]Chemical Sciences/Coordination chemistry, Hydrogenation, Hidrogenació
Abstract

International audience; New Rh-NPs stabilised by N-Heterocyclic Carbenes (NHC) were synthesized by decomposition of [Rh(η3-C3H5)3] under H2 atmosphere and fully characterized. Surface studies by FT-IR and NMR spectroscopy employing isotopically labelled ligands were also performed. The Rh0.2 NPs are active catalysts in the reduction of various aromatic substrates. In the reduction of phenol, high selectivities to cyclohexanone or cyclohexanol were obtained depending on the reaction conditions. However, this catalytic system exhibited much lower activity in the hydrogenation of substituted phenols. Pyridine was easily hydrogenated under mild conditions and interestingly, the hydrogenation of 4-methyl and 4-trifluoromethylpyridine resulted slower than that of 2-methylpyridine. The hydrogenation of 1-(pyridin-2-yl)propan-2-one provided the β-enaminone 13a in high yield as a consequence of the partial reduction of the pyridine ring followed by isomerization. Quinoline could be either partially hydrogenated to 1,2,3,4-tetrahydroquinoline or fully reduced to decahydroquinoline by adjusting the reaction conditions.

Published
2017
Full Text
View/download PDF

34. Magnetic hyperthermia in single-domain monodisperse FeCo nanoparticles: Evidences for Stoner–Wohlfarth behavior and large losses.

Author

Lacroix, L.-M., Malaki, R. Bel, Carrey, J., Lachaize, S., Respaud, M., Goya, G. F., and Chaudret, B.

Subjects
MAGNETIC fields, FERROMAGNETISM, NANOPARTICLES, MAGNETICS, MAGNETISM, MAGNETIZATION
Abstract

We report on hyperthermia measurements on a colloidal solution of 14.2±1.5 nm monodisperse FeCo nanoparticles (NPs). Losses as a function of the magnetic field display a sharp increase followed by a plateau, which is what is expected for losses of ferromagnetic single-domain NPs. The frequency dependence of the coercive field is deduced from hyperthermia measurement and is in quantitative agreement with a simple model of noninteracting NPs. The measured losses (1.5 mJ/g) compare to the highest of the literature, although the saturation magnetization of the NPs is well below the bulk one. [ABSTRACT FROM AUTHOR]

Published
2009
Full Text
View/download PDF

35. Chemisorption on nickel nanoparticles of various shapes: Influence on magnetism.

Author

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

Subjects
CHEMISORPTION, NICKEL, NANOPARTICLES, SPECTRUM analysis, X-ray diffraction
Abstract

Nanoparticles of nickel have been obtained in solution through reaction of an organometallic precursor, Ni(COD)[sub 2] (COD=cycloocta-1,5-diene), with dihydrogen, in the presence of various stabilizing agents. X-ray diffraction studies evidence a face-centered-cubic structure for all samples. Spherical isolated superparamagnetic nanoparticles (d∼4.5 nm) are produced in the presence of poly(N-vinylpyrrolid-2-one). They display a magnetization value comparable to that of bulk nickel, as determined from superconducting quantum iinterference device (SQUID) measurements. Exposure of the surface of the nanoparticles to CO, leading to CO coordination as monitored by infrared spectroscopy, or to methanol, strongly reduces their magnetization. This reduction corresponds respectively to one or two magnetically inactive layers of nickel atoms at the nanoparticles surface. The production of elongated nanoparticles was favored when either trioctylphosphineoxide or hexadecylamine (HDA) were used as stabilizing agents. In this case, SQUID measurements show that only HDA preserves the magnetization of the surface. This stabilizing agent was selected for the production of nickel nanorods. The influence of ligands on the effective anisotropy is discussed. © 2003 American Institute of Physics. [ABSTRACT FROM AUTHOR]

Published
2003
Full Text
View/download PDF

36. Magnetic anisotropy determination and magnetic hyperthermia properties of small Fe nanoparticles in the superparamagnetic regime

Author

Mehdaoui, B., Meffre, A., Lacroix, L.-M., Carrey, J., Lachaize, S., Respaud, M., Gougeon, M., and Chaudret, B.

Subjects
Iron -- Magnetic properties, Iron -- Thermal properties, Magnetization -- Analysis, Medical equipment -- Innovations, Physiological apparatus -- Innovations, Nanotechnology -- Research, Physics
Abstract

Several studies are conducted to explain the magnetic anisotropy, as well as the hyperthermia properties of the various small Fe nanoparticles present in the superparamagnetic regime. The specific absorption rate of these nanoparticles is shown to be completely dependent on their magnetic field.

Published
2010

37. Ultrasmall iron nanoparticles: effect of size reduction on anisotropy and magnetization

Author

Lacroix, L.-M., Lachaize, S., Falqui, A., Blon, T., Carrey, J., Respaud, M., Dumestre, F., Amiens, C., Margeat, O., Chaudret, B., Lecante, P., and Snoeck, E.

Subjects
Anisotropy -- Analysis, Iron -- Magnetic properties, Mossbauer spectroscopy -- Usage, Superconducting quantum interference devices -- Usage, Physics
Abstract

The synthesis and characterization of nanoparticles (NPs) with magnetic properties close to those of bulk are described by using superconducting quantum interference device (SQUID) and Mossbauer measurements. The magnetic anisotropy energy constant has increased up to ten times the bulk one.

Published
2008

40. The big impact of a small detail: Cobalt nanocrystal polymorphism as a result of precursor addition rate during stock solution preparation

Author

Liakakos, N. Cormary, B. Li, X. Lecante, P. Respaud, M. Maron, L. Falqui, A. Genovese, A. Vendier, L. Koïnis, S. Chaudret, B. Soulantica, K.

Abstract

The control of nanocrystal structures at will is still a challenge, despite the recent progress of colloidal synthetic procedures. It is common knowledge that even small modifications of the reaction parameters during synthesis can alter the characteristics of the resulting nano-objects. In this work we report an unexpected factor which determines the structure of cobalt nanoparticles. Nanocrystals of distinctly different sizes and shapes have resulted from stock solutions containing exactly the same concentrations of [CoN(SiMe 3) 2 2(thf)], hexadecylamine, and lauric acid. The reduction reaction itself has been performed under identical conditions. In an effort to explain these differences and to analyze the reaction components and any molecular intermediates, we have discovered that the rate at which the cobalt precursor is added to the ligand solution during the stock solution preparation at room temperature becomes determinant by triggering off a nonanticipated side reaction which consumes part of the lauric acid, the main stabilizing ligand, transforming it to a silyl ester. Thus, an innocent mixing, apparently not related to the main reaction which produces the nanoparticles, becomes the parameter which in fine defines nanocrystal characteristics. This side reaction affects in a similar way the morphology of iron nanoparticles prepared from an analogous iron precursor and the same long chain stabilizing ligands. Side reactions are potentially operational in a great number of systems yielding nanocrystals, despite the fact that they are very rarely mentioned in the literature. © 2012 American Chemical Society.

Published
2012

41. On the Loading of Composite Materials with Nickel Nanorods for the Enhancement of Electrical Conductivity

Author

Mourdikoudis, S., Fau, P., Kahn, M., Chaudret, B., Lantin, B., Bley, Vincent, Laboratoire de chimie de coordination (LCC), Institut de Chimie de Toulouse (ICT), Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche pour le Développement (IRD)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS), Institut Paoli-Calmettes, Fédération nationale des Centres de lutte contre le Cancer (FNCLCC), Laboratoire de physique et chimie des nano-objets (LPCNO), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut National des Sciences Appliquées (INSA)-Université de Toulouse (UT)-Institut de Chimie de Toulouse (ICT), Université de Toulouse (UT)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS), Unité mixte de recherche génétique et horticulture Genhort, Université d'Angers (UA)-Institut National de la Recherche Agronomique (INRA)-Institut National d'Horticulture, Matériaux Diélectriques dans la Conversion d’Energie (LAPLACE-MDCE), LAboratoire PLasma et Conversion d'Energie (LAPLACE), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut National Polytechnique (Toulouse) (Toulouse INP), Université de Toulouse (UT)-Université Toulouse III - Paul Sabatier (UT3), and Université de Toulouse (UT)

Subjects
[SPI.NRJ]Engineering Sciences [physics]/Electric power
Abstract

International audience

Published
2011

43. Synthesis of new RuO2@SiO2 composite nanomaterials and their application as catalytic filters for selective detection of gas sensors

Author

Jansat, S., Pelzer, K., Garcia-Anton, J., Philippot, K., Maisonat, A., Chaudret, B., Guari, Y., Mehdi, A., Reyé, C., and Corriu, R.

Abstract

RuO2@SiO2 nanomaterials have been prepared using hybrid mesostructured silica (EtO)2P(O)(CH2)3SiO1.5/xSiO2 (x = 9, 16) by anchoring the metal precursor Ru(COD)(COT) (COD = 1, 3-cyclooctadiene, COT = 1, 3, 5-cyclooctatriene) within the pores of the organized silica matrix taking profit of the phosphonate moieties followed by i) decomposition under dihydrogen at room temperature in THF to achieve ruthenium nanoparticles containing materials and ii) a solid state thermal treatment at 450°C under air. The so-obtained RuO2@SiO2 nanomaterials were evaluated as catalytic filters when deposited onto gas sensors for the preferential detection of propane in a multicomponent gas mixture propane/carbon monoxide/nitrogen dioxide. The Ru and RuO2 nanoparticles containing materials have been characterised by elemental analysis, Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD), nitrogen sorption measurements and 31P and 13C Nuclear Magnetic Resonance (NMR).

Published
2007

47. Long-chain NHC-stabilized RuNPs as versatile catalysts for one-pot oxidation/hydrogenation reactions.

Author

Martínez-Prieto, L. M., Ferry, A., Rakers, L., Richter, C., Lecante, P., Philippot, K., Chaudret, B., and Glorius, F.

Subjects
RUTHENIUM compound synthesis, CARBENES, METAL catalysts, OXIDATION, HYDROGENATION, CATALYTIC activity
Abstract

The synthesis and catalytic activity of long-chain NHC-stabilized RuNPs are presented. Full characterization of these novel nanostructures including surface state studies show that the ligand influences the number and the location of Ru active sites which impacts the NP catalytic activity, especially in hydrogenation reactions. The high stability and versatility of these nanosystems make them successful catalysts for both oxidation and hydrogenation reactions that can even be performed successively in a one pot-fashion. [ABSTRACT FROM AUTHOR]

Published
2016
Full Text
View/download PDF

48. A betaine adduct of N-heterocyclic carbene and carbodiimide, an efficient ligand to produce ultra-small ruthenium nanoparticles.

Author

Martínez-Prieto, L. M., Urbaneja, C., Palma, P., Cámpora, J., Philippot, K., and Chaudret, B.

Subjects
BETAINE, NANOSTRUCTURED materials, PLATINUM group, RUTHENIUM compounds, SUPRAMOLECULAR chemistry, BIOMACROMOLECULES
Abstract

The betaine adduct of N-heterocyclic carbene and carbodiimide (ICy·(p-tol)NCN) was found to be a very efficient ligand to prepare very small (1–1.3 nm) ruthenium nanoparticles (RuNPs). The coordination of the ligand on the metal surface takes place through the carbodiimide moiety. The resulting RuNPs led to decarbonylation of THF and showed size selectivity for styrene hydrogenation. [ABSTRACT FROM AUTHOR]

Published
2015
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results