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Your search keyword '"David Portehault"' showing total 4 results
Start Over Author "David Portehault" Journal chemistry of materials
4 results on '"David Portehault"'

1. Hydroxyapatites as Versatile Inorganic Hosts of Unusual Pentavalent Manganese Cations

Author

María Hernando, José M. González-Calbet, Marina Parras, Christel Laberty-Robert, Aurea Varela, Gwenaëlle Rousse, José Luis Martínez, Laura Serrador, David Portehault, María Teresa Fernández-Díaz, Francisco Gonell, E. Matesanz, Clément Sanchez, Isabel Gómez-Recio, Almudena Torres-Pardo, Universidad Complutense de Madrid = Complutense University of Madrid [Madrid] (UCM), Institut Laue-Langevin (ILL), ILL, Laboratoire des Sciences du Numérique de Nantes (LS2N), IMT Atlantique Bretagne-Pays de la Loire (IMT Atlantique), Institut Mines-Télécom [Paris] (IMT)-Institut Mines-Télécom [Paris] (IMT)-Université de Nantes - UFR des Sciences et des Techniques (UN UFR ST), Université de Nantes (UN)-Université de Nantes (UN)-École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Novel Advanced Nano-Objects (LCMCP-NANO), Matériaux Hybrides et Nanomatériaux (LCMCP-MHN), Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Laboratoire de Chimie de la Matière Condensée de Paris (LCMCP), Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU), Chaire Chimie des matériaux hybrides, and Reactive Materials for Electrochemical Systems (LCMCP-RMES )

Subjects
Chemistry, General Chemical Engineering, chemistry.chemical_element, [CHIM.MATE]Chemical Sciences/Material chemistry, 02 engineering and technology, General Chemistry, Manganese, 010402 general chemistry, 021001 nanoscience & nanotechnology, 01 natural sciences, 0104 chemical sciences, Polymer chemistry, Materials Chemistry, Hydroxyapatites, 0210 nano-technology
Abstract

International audience; Contrary to molecular species, only very few solids are reported to host manganese (V) species. Herein, we report three new compounds with a hydroxyapatite structural backbone built on the Mn V O 4 3− anion: Sr 5 [(Mn 1−x Si x)O 4 ] 3 (OH) 1−3x (x =0 and 0.053), Sr 5 (MnO 4) 3 (OH) 1−y F y (y = 0.90), and Sr 5 [(Mn 1−x Si x)-O 4 ] 3 F 1−3x (x = 0.058). These solids are fully characterized using powder X-ray and neutron powder diffraction, scanning transmission electron microscopy, electron energy loss spectroscopy (EELS), thermogravimetric analysis, and magnetic measurements. Especially, we report for the first time EELS Mn−L 2,3 spectra of manganese with the oxidation state (V). Contrary to other Mn(V) oxides, these solids and the nominal compound Sr 5 (MnO 4) 3 OH do not comprise Ba 2+ cations but rely only on Sr 2+ cations, showing that barium is not a required element to stabilize Mn(V) species in inorganic solids. We show that by tuning soft chemistry conditions on the one hand and post-treatment topological transformation conditions on the other hand, Mn(V) and hydroxyl groups can be substituted by Si(IV) and fluoride ions, respectively. Hence, we deliver solids with a potentially wide composition range. These compounds show significant oxygen anionic conduction, thus suggesting the emergence of new functional materials built from high-oxidation state manganese cations.

Published
2020

2. Morphology Control of Cryptomelane Type MnO2 Nanowires by Soft Chemistry. Growth Mechanisms in Aqueous Medium

Author

Sophie Cassaignon, David Portehault, Jean-Pierre Jolivet, and E. Baudrin

Subjects
Diffraction, Materials science, General Chemical Engineering, Nanowire, Nanoparticle, Nanotechnology, General Chemistry, engineering.material, Soft chemistry, Chemical engineering, Electron diffraction, Transmission electron microscopy, Materials Chemistry, engineering, Cryptomelane, Nanorod
Abstract

Nanowires of one-dimensional manganese oxide (cryptomelane) have been synthesized using reaction between MnII (MnSO4) and MnVII (KMnO4) in water by a low-temperature route at 60 °C and 95 °C. Characterization of the nanoparticles was carried out using powder X-ray diffraction, transmission electron microscopy, electron diffraction, and nitrogen adsorption−desorption. Two synthesis methods were developed depending whether the pH was initially adjusted or fixed all along the solid formation. Both methods exhibited variation of the nanowire morphology with diameter, length, and specific area varying in the 15−40 nm, 0.1−1.1 μm, and 35−110 m2·g-1 ranges, respectively, depending on the growth conditions (acidity and temperature). The growth mechanism of the nanowires was proved to proceed by oriented attachment of primary 10 nm width nanorods for the lateral direction and dissolution−crystallization for the longitudinal direction. The diameter variation with acidic conditions was interpreted in terms of electr...

Published
2007

3. Design of Hierarchical Core−Corona Architectures of Layered Manganese Oxides by Aqueous Precipitation.

Author

David Portehault, Emmanuel Baudrin, Jean-Pierre Jolivet, and Sophie Cassaignon

Subjects
*MANGANESE oxides, *PRECIPITATION (Chemistry), *ELECTRON diffraction, *SURFACE chemistry
Abstract

A low temperature (60 or 95 °C), “one-pot” procedure for aqueous precipitation of layered manganese oxide core@shell particles is developed, based on the reaction between MnO 4−and Mn 2+. Characterization of the particles was carried out using powder XRD, nitrogen adsorption−desorption, FESEM, TEM, and electron diffraction. Textural and morphological tailoring is achieved through various experimental parameters, with the specific surface area adjusted between 15 and 110 m 2g −1while a ball-like or sheetlike shape is selectively obtained. The synthesis is based on a two-step precipitation process, with the first stage involving in situ seeding and enabling shape control via adjustment of the initial acidity. Hierarchical core−corona particles are obtained through a second slower heterogeneous nucleation stage, controlled by reactant ratio, aging time, temperature, and acidity of the aging medium. [ABSTRACT FROM AUTHOR]

Published
2008
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4. Morphology Control of Cryptomelane Type MnO2Nanowires by Soft Chemistry. Growth Mechanisms in Aqueous Medium.

Author

David Portehault, Sophie Cassaignon, Emmanuel Baudrin, and Jean-Pierre Jolivet

Subjects
*NANOSTRUCTURED materials, *NANOWIRES, *ELECTRON microscopy, *ELECTRIC wire
Abstract

Nanowires of one-dimensional manganese oxide (cryptomelane) have been synthesized using reaction between MnII(MnSO4) and MnVII(KMnO4) in water by a low-temperature route at 60 °C and 95 °C. Characterization of the nanoparticles was carried out using powder X-ray diffraction, transmission electron microscopy, electron diffraction, and nitrogen adsorption−desorption. Two synthesis methods were developed depending whether the pH was initially adjusted or fixed all along the solid formation. Both methods exhibited variation of the nanowire morphology with diameter, length, and specific area varying in the 15−40 nm, 0.1−1.1 m, and 35−110 m2·g-1ranges, respectively, depending on the growth conditions (acidity and temperature). The growth mechanism of the nanowires was proved to proceed by oriented attachment of primary 10 nm width nanorods for the lateral direction and dissolution−crystallization for the longitudinal direction. The diameter variation with acidic conditions was interpreted in terms of electrostatic interactions between primary nanorods. [ABSTRACT FROM AUTHOR]

Published
2007
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