A5019320920- Advanced Condensed Matter Physics
- Magnetic and transport properties of perovskites and related materials
- X-ray Diffraction in Crystallography
- Multiferroics and related materials
- Crystallization and Solubility Studies
- Iron-based superconductors research
- Crystal Structures and Properties
- Electronic and Structural Properties of Oxides
- Fullerene Chemistry and Applications
- Physics of Superconductivity and Magnetism
- Magnetic Properties and Synthesis of Ferrites
- Graphene research and applications
- Luminescence Properties of Advanced Materials
- Microstructure and Mechanical Properties of Steels
- Nuclear materials and radiation effects
- Inorganic Chemistry and Materials
- High-pressure geophysics and materials
- High Temperature Alloys and Creep
- Metal Alloys Wear and Properties
- Advanced X-ray Imaging Techniques
- Chalcogenide Semiconductor Thin Films
- Copper-based nanomaterials and applications
- Pigment Synthesis and Properties
- Iron oxide chemistry and applications
- Advancements in Solid Oxide Fuel Cells
Institut Néel
2010-2023
Centre National de la Recherche Scientifique
2008-2023
Université Grenoble Alpes
2010-2023
Institut polytechnique de Grenoble
2023
Centro de Estudios y Experimentación de Obras Públicas
2021
Université Joseph Fourier
2009-2016
University of Antwerp
2008-2010
Universität Innsbruck
2010
University of Bern
2010
École Nationale Supérieure d'Ingénieurs de Caen
2004-2010
An extended use of synchrotron-based X-ray diffraction microtomography (XRD-µCT) to study simultaneously the phase distribution and microstructure in phase-transformation processes is proposed. This three-dimensional non-invasive imaging approach has been applied understand transformation C60 rhombohedral polymer (C60R) into disordered graphite (DG) at high pressure temperature. The heterogeneous sample was synthesized (5 GPa, 1100 K) using a Paris–Edinburgh cell selective image...
Different samples of the ferrite "Sr4Fe6O13", synthesized in air, nitrogen, and argon, have been studied by high-resolution electron microscopy. It is shown that this oxide oxygen-deficient, i.e., Sr4Fe6O13-δ, its structure modulated. The diffraction study shows modulation vector pa⃗* + qc⃗*, with p = (1 − δ)/2 varying range [0.4−0.5] q close to 1. component along c⃗ induces complex modulated structures. also demonstrated oxygen nonstoichiometry corresponds generation microphases...
Abstract Pnictogens and chalcogens are both viable anions for promoting Fe-based superconductivity, intense research activity in the related families has established a systematic correlation between Fe-anion height superconducting critical temperature T c , with an optimum of ~1.38 Å. Here, we report discovery superconductivity compound LaFeSiO 1− δ that incorporates crystallogen element, Si, challenges above picture: considering strongly squeezed Fe–Si 0.94 Å, transition at = 10 K is...
Mixed anion oxyhalides with the formula Ca2MnO3X (X = Cl, Br) are synthesized using solid-state reaction methods. These two materials crystallize in a novel structure type due to small ionic radius of Ca and strong Jahn-Teller effect Mn3+. The resulting (space group Cmcm) contains one-dimensional chains MnO4 square planes, an angle ∼120° between neighboring planes. At low temperatures, adopt magnetic arrangements, ferromagnetic coupled antiferromagnetically. On applying field, both...
For the composition (Sr0.61Pb0.18)(Fe0.75Mn0.25)O2.29, a new modulated crystallographic shear structure, related to perovskite, has been synthesized and structurally characterized by transmission electron microscopy. The structure can be described using monoclinic supercell with cell parameters am = 27.595(2) Å, bm 3.8786(2) cm 13.3453(9) βm 100.126(5)°, refined from powder X-ray diffraction data. incommensurate phases require an alternative approach superspace formalism. This allows unified...
The origin of the incommensurability in crystallographic shear (CS) structure ferri-Manganite (Sr0.61Pb0.18)(Fe0.75Mn0.25)O2.29, related to cation deficient perovskite, has been determined by careful analysis boundaries between two variants constituting phasoid. High Resolution Electron Microscopy/HAADF-STEM images allow structural mechanisms be understood through presence units common both phases, responsible incommensurate character observed electron diffraction patterns. allows for...
A new ferrite Bi4Sr14Fe24O56 (i.e., Bi4/3Sr14/3Fe8O18.66) has been synthesized. The high-resolution electron microscopy study of this oxide shows that its modulated structure consists an original intergrowth double perovskite layers [(Sr,Bi)2Fe2O6] with oxygen-deficient [(Sr,Bi)2Fe4O7-δ] layers. latter are closely related to the [Sr2Fe4O7-δ] observed in Sr4Fe6O13, is, built up FeO5 bipyramids and distorted tetragonal pyramids. This appears as member m = 2 a potential series [(Sr,Bi)2Fe2O6]m,...
A new Tl-doped strontium ferrite Fe2(Sr2-ϵTlϵ)Sr3Fe4O14.65, with an original structure, has been synthesized and structurally characterized by powder X-ray diffraction transmission electron microscopy. The TGA Mössbauer studies evidence a mixed valence of iron. structure exhibits commensurate modulation, F-type subcell ≈ b 5.4 Å (≈ ap√2), c 42 modulation vector q⃗ = αa⃗* α 0.4. supercell parameters have refined as a= 27.1101(8) Å, b= 5.5187(2) c= 42.0513(9) in the space group Fmmm....
By suitably combining diffraction/scattering and tomography (DSCT), it is possible to access selective submicron 2D/3D structural micro-structural information, which cannot be obtained from separate, independent diffraction experiments. DSCT used discriminate between multi-phase crystalline amorphous materials, especially when the similarities in densities limit use of other methods. In addition, this method sensitive local variation state, texture, grain size or strains inside object can...
We report on the discovery of a Ba-based chromate obtained by high pressure–high temperature treatment low pressure orthorhombic Ba2CrO4 phase. By combining transmission electron microscopy and powder X-ray diffraction measurements, we have determined its crystallographic structure. This new Cr-oxide has cubic lattice with = 13.3106(6) Å built from three-dimensional network two Cr sites, Cr1 Cr2, both in octahedral environments, face sharing between Cr2 octahedra corner-sharing octahedra....
Magnetically frustrated materials have been the subject of many studies over last decades. In search for a 3-dimensional quantum spin liquid, where quantum-mechanical fluctuations prevent magnetic order, different phases stoichiometry Ba3NiSb2O9 recently [1] synthesized some them at high pressure. Two these are hexagonal. The hexagonal (space groups P63/mmc and P63mc, respectively) structures but cell parameters that differ by less than 1%. Similar obtained with Cu [2] or Co [3]. These well...
Pyroxene compounds are a common form of natural minerals and have been studied as such for long time. More recently the research on quasi-one-dimensional magnetic multiferroïc materials has renewed interest in pyroxenes stoichiometry AMX2O6 (A = alkali metal, M transition X Si or Ge), since M3+ ions chains. Chemical substitution A sites can change coupling along these chains making this system rich field exploration new phases interesting properties [1]. In work we report discovery phase...
These past few years, many new structures have been solved using electron diffraction methods: zone axis precession (PED) and tomography in reciprocal space. Both methods enable to reduce importantly the multiple scattering, so that reflection intensities can be used for structure determination by direct methods. The ferrite Sr25Fe30O77 belongs a family of phases whose consist an intergrowth m perovskite layers with complex rocksalt type [1,2]. compound interest is member = 4 this its has...