The Experts below are selected from a list of 192 Experts worldwide ranked by ideXlab platform
Marie-anne Arrio - One of the best experts on this subject based on the ideXlab platform.
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Single-Ion Magnetism in the Extended Solid-State: Insights from X-ray Absorption and Emission Spectroscopy
Chemical Science, 2020Co-Authors: Myron S. Huzan, M. Fix, Matteo Aramini, Peter Bencok, J. Frederick W. Mosselmans, Shusaku Hayama, Franziska Breitner, Leland B. Gee, Charles J. Titus, Marie-anne ArrioAbstract:Large single-ion magnetic anisotropy is observed in Lithium Nitride doped with iron. The iron sites are two-coordinate, putting iron doped Lithium Nitride amongst a growing number of two coordinate transition metal single-ion magnets (SIMs). Uniquely, the relaxation times to magnetisation reversal are over two orders of magnitude longer in iron doped Lithium Nitride than other 3d-metal SIMs, and comparable with high-performance lanthanide-based SIMs. To understand the origin of these enhanced magnetic properties a detailed characterisation of electronic structure is presented. Access to dopant electronic structure calls for atomic specific techniques, hence a combination of detailed single-crystal X-ray absorption and emission spectroscopies are applied. Together K-edge, L2,3-edge and Kβ X-ray spectroscopies probe local geometry and electronic structure, identifying iron doped Lithium Nitride to be a prototype, solid-state SIM, clean of stoichiometric vacancies where Fe lattice sites are geometrically equivalent. Extended X-ray absorption fine structure and angular dependent single-crystal X-ray absorption near edge spectroscopy measurements determine FeI dopant ions to be linearly coordinated, occupying a D6h symmetry pocket. The dopant engages in strong 3dπ-bonding, resulting in an exceptionally short Fe–N bond length (1.873(7) A) and rigorous linearity. It is proposed that this structure protects dopant sites from Renner–Teller vibronic coupling and pseudo Jahn–Teller distortions, enhancing magnetic properties with respect to molecular-based linear complexes. The Fe ligand field is quantified by L2,3-edge XAS from which the energy reduction of 3dz2 due to strong 4s mixing is deduced. Quantification of magnetic anisotropy barriers in low concentration dopant sites is inhibited by many established methods, including far-infrared and neutron scattering. We deduce variable temperature L3-edge XAS can be applied to quantify the J = 7/2 magnetic anisotropy barrier, 34.80 meV (∼280 cm−1), that corresponds with Orbach relaxation via the first excited, MJ = ±5/2 doublet. The results demonstrate that dopant sites within solid-state host lattices could offer a viable alternative to rare-earth bulk magnets and high-performance SIMs, where the host matrix can be tailored to impose high symmetry and control lattice induced relaxation effects.
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Single-ion magnetism in the extended solid-state: insights from X-ray absorption and emission spectroscopy
Chemical Science, 2020Co-Authors: Myron S. Huzan, M. Fix, Matteo Aramini, Peter Bencok, J. Frederick W. Mosselmans, Shusaku Hayama, Franziska Breitner, Leland Gee, Charles Titus, Marie-anne ArrioAbstract:Large single-ion magnetic anisotropy is observed in Lithium Nitride doped with iron. The iron sites are twocoordinate, putting iron doped Lithium Nitride amongst a growing number of two coordinate transition metal single-ion magnets (SIMs). Uniquely, the relaxation times to magnetisation reversal are over two orders of magnitude longer in iron doped Lithium Nitride than other 3d-metal SIMs, and comparable with high-performance lanthanide-based SIMs. To understand the origin of these enhanced magnetic properties a detailed characterisation of electronic structure is presented. Access to dopant electronic structure calls for atomic specific techniques, hence a combination of detailed single-crystal X-ray absorption and emission spectroscopies are applied. Together K-edge, L 2,3-edge and Kb X-ray spectroscopies probe local geometry and electronic structure, identifying iron doped Lithium Nitride to be a prototype, solid-state SIM, clean of stoichiometric vacancies where Fe lattice sites are geometrically equivalent. Extended X-ray absorption fine structure and angular dependent single-crystal X-ray absorption near edge spectroscopy measurements determine Fe I dopant ions to be linearly coordinated, occupying a D 6h symmetry pocket. The dopant engages in strong 3dp-bonding, resulting in an exceptionally short Fe-N bond length (1.873(7)Å) and rigorous linearity. It is proposed that this structure protects dopant sites from Renner-Teller vibronic coupling and pseudo Jahn-Teller distortions, enhancing magnetic properties with respect to molecular-based linear complexes. The Fe ligand field is quantified by L 2,3-edge XAS from which the energy reduction of 3d z 2 due to strong 4s mixing is deduced. Quantification of magnetic anisotropy barriers in low concentration dopant sites is inhibited by many established methods, including far-infrared and neutron scattering. We deduce variable temperature L 3edge XAS can be applied to quantify the J ¼ 7/2 magnetic anisotropy barrier, 34.80 meV ($280 cm À1), that corresponds with Orbach relaxation via the first excited, M J ¼ AE5/2 doublet. The results demonstrate that dopant sites within solid-state host lattices could offer a viable alternative to rare-earth bulk magnets and high-performance SIMs, where the host matrix can be tailored to impose high symmetry and control lattice induced relaxation effects.
Michel Latroche - One of the best experts on this subject based on the ideXlab platform.
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Mechanochemistry of Lithium Nitride under hydrogen gas
Phys. Chem. Chem. Phys., 2015Co-Authors: Zhi-min Li, Michel Latroche, Shuihua Wang, J. Du, Jianzhong Zhang, L Jiang, Fermin CuevasAbstract:Hydrogen uptake during the mechanochemistry of Lithium Nitride under 9 MPa hydrogen pressure has been analyzed by means of in situ solid-gas absorption and ex situ X-ray diffraction (XRD) measurements. In situ hydrogenation curves show two H-sorption steps leading to an overall hydrogen uptake of 9.8 wt% H after 3 hours of milling. The milled end-products consist of nanocrystalline (∼10 nm) LiNH2 and LiH phases. The first reaction step comprises the transformation of the polymorph α-Li3N (S.G. P6/mmm) into the β-Li3N (S.G. P63/mmc) metastable phase and the reaction of the latter with hydrogen to form Lithium imide: β-Li3N + H2 → Li2NH + LiH. Reaction kinetics of the first step is zero-order. Its rate-limiting control is assigned to the collision frequency between milling balls and Li3N powder. In the second absorption step, Lithium imide converts to Lithium amide following the reaction scheme Li2NH + H2 → LiNH2 + LiH. Reaction kinetics is here limited by one-dimensional nucleation and the growth mechanism, which, in light of structural data, is assigned to the occurrence of Lithium vacancies in the imide compound. This study provides new insights into the reaction paths and chemical kinetics of light hydrogen storage materials during their mechanochemical synthesis.
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Li3−xMxN (M=Co, Ni) synthesized by Spark Plasma Sintering for hydrogen storage
Journal of Alloys and Compounds, 2011Co-Authors: Junxian Zhang, Radovan Černý, Benjamin Villeroy, Claude Godart, Dhanesh Chandra, Michel LatrocheAbstract:Lithium Nitride has recently emerged as a promising material for hydrogen storage. The hydrogen storage capacity reaches 10.2 wt% H by the formation of compounds, such as imides, amides, and others. Hydrogenation of Lithium Nitride is highly exothermic, and thus desorbing hydrogen from these compounds requires high temperature and cannot be used for reversible hydrogen storage. Ab initio calculations predict that partial substitution of Li by transition metals like Cu or Ni can reduce the reaction enthalpy between amide and imide. In this work, we present the synthesis of the ternary system Li3−xMxN (M = Co or Ni) by Spark Plasma Sintering (SPS). The samples are hydrogenated at 255 °C by solid gas reaction. The sample crystal structures have been analyzed by synchrotron X-ray powder diffraction using a high resolution powder diffractometer. The structural models for Co and Ni-substituted Li3N have been confirmed The effect of the substitution on the phase formation upon hydrogenation has been investigated at various metal and hydrogen concentration. Different behaviors are observed depending on the nature of M
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Li3−xMxN (M = Co, Ni) synthesized by Spark Plasma Sintering for hydrogen storage
Journal of Alloys and Compounds, 2010Co-Authors: Junxian Zhang, Radovan Černý, Benjamin Villeroy, Claude Godart, Dhanesh Chandra, Michel LatrocheAbstract:Abstract Lithium Nitride has recently emerged as a promising material for hydrogen storage. The hydrogen storage capacity reaches 10.2 wt% H by the formation of compounds, such as imides, amides, and others. Hydrogenation of Lithium Nitride is highly exothermic, and thus desorbing hydrogen from these compounds requires high temperature and cannot be used for reversible hydrogen storage. Ab initio calculations predict that partial substitution of Li by transition metals like Cu or Ni can reduce the reaction enthalpy between amide and imide. In this work, we present the synthesis of the ternary system Li 3− x M x N ( M = Co or Ni) by Spark Plasma Sintering (SPS). The samples are hydrogenated at 255 °C by solid gas reaction. The sample crystal structures have been analyzed by synchrotron X-ray powder diffraction using a high resolution powder diffractometer. The structural models for Co and Ni-substituted Li 3 N have been confirmed. The effect of the substitution on the phase formation upon hydrogenation has been investigated at various metal and hydrogen concentration. Different behaviors are observed depending on the nature of M .
Myron S. Huzan - One of the best experts on this subject based on the ideXlab platform.
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Single-Ion Magnetism in the Extended Solid-State: Insights from X-ray Absorption and Emission Spectroscopy
Chemical Science, 2020Co-Authors: Myron S. Huzan, M. Fix, Matteo Aramini, Peter Bencok, J. Frederick W. Mosselmans, Shusaku Hayama, Franziska Breitner, Leland B. Gee, Charles J. Titus, Marie-anne ArrioAbstract:Large single-ion magnetic anisotropy is observed in Lithium Nitride doped with iron. The iron sites are two-coordinate, putting iron doped Lithium Nitride amongst a growing number of two coordinate transition metal single-ion magnets (SIMs). Uniquely, the relaxation times to magnetisation reversal are over two orders of magnitude longer in iron doped Lithium Nitride than other 3d-metal SIMs, and comparable with high-performance lanthanide-based SIMs. To understand the origin of these enhanced magnetic properties a detailed characterisation of electronic structure is presented. Access to dopant electronic structure calls for atomic specific techniques, hence a combination of detailed single-crystal X-ray absorption and emission spectroscopies are applied. Together K-edge, L2,3-edge and Kβ X-ray spectroscopies probe local geometry and electronic structure, identifying iron doped Lithium Nitride to be a prototype, solid-state SIM, clean of stoichiometric vacancies where Fe lattice sites are geometrically equivalent. Extended X-ray absorption fine structure and angular dependent single-crystal X-ray absorption near edge spectroscopy measurements determine FeI dopant ions to be linearly coordinated, occupying a D6h symmetry pocket. The dopant engages in strong 3dπ-bonding, resulting in an exceptionally short Fe–N bond length (1.873(7) A) and rigorous linearity. It is proposed that this structure protects dopant sites from Renner–Teller vibronic coupling and pseudo Jahn–Teller distortions, enhancing magnetic properties with respect to molecular-based linear complexes. The Fe ligand field is quantified by L2,3-edge XAS from which the energy reduction of 3dz2 due to strong 4s mixing is deduced. Quantification of magnetic anisotropy barriers in low concentration dopant sites is inhibited by many established methods, including far-infrared and neutron scattering. We deduce variable temperature L3-edge XAS can be applied to quantify the J = 7/2 magnetic anisotropy barrier, 34.80 meV (∼280 cm−1), that corresponds with Orbach relaxation via the first excited, MJ = ±5/2 doublet. The results demonstrate that dopant sites within solid-state host lattices could offer a viable alternative to rare-earth bulk magnets and high-performance SIMs, where the host matrix can be tailored to impose high symmetry and control lattice induced relaxation effects.
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Single-ion magnetism in the extended solid-state: insights from X-ray absorption and emission spectroscopy
Chemical Science, 2020Co-Authors: Myron S. Huzan, M. Fix, Matteo Aramini, Peter Bencok, J. Frederick W. Mosselmans, Shusaku Hayama, Franziska Breitner, Leland Gee, Charles Titus, Marie-anne ArrioAbstract:Large single-ion magnetic anisotropy is observed in Lithium Nitride doped with iron. The iron sites are twocoordinate, putting iron doped Lithium Nitride amongst a growing number of two coordinate transition metal single-ion magnets (SIMs). Uniquely, the relaxation times to magnetisation reversal are over two orders of magnitude longer in iron doped Lithium Nitride than other 3d-metal SIMs, and comparable with high-performance lanthanide-based SIMs. To understand the origin of these enhanced magnetic properties a detailed characterisation of electronic structure is presented. Access to dopant electronic structure calls for atomic specific techniques, hence a combination of detailed single-crystal X-ray absorption and emission spectroscopies are applied. Together K-edge, L 2,3-edge and Kb X-ray spectroscopies probe local geometry and electronic structure, identifying iron doped Lithium Nitride to be a prototype, solid-state SIM, clean of stoichiometric vacancies where Fe lattice sites are geometrically equivalent. Extended X-ray absorption fine structure and angular dependent single-crystal X-ray absorption near edge spectroscopy measurements determine Fe I dopant ions to be linearly coordinated, occupying a D 6h symmetry pocket. The dopant engages in strong 3dp-bonding, resulting in an exceptionally short Fe-N bond length (1.873(7)Å) and rigorous linearity. It is proposed that this structure protects dopant sites from Renner-Teller vibronic coupling and pseudo Jahn-Teller distortions, enhancing magnetic properties with respect to molecular-based linear complexes. The Fe ligand field is quantified by L 2,3-edge XAS from which the energy reduction of 3d z 2 due to strong 4s mixing is deduced. Quantification of magnetic anisotropy barriers in low concentration dopant sites is inhibited by many established methods, including far-infrared and neutron scattering. We deduce variable temperature L 3edge XAS can be applied to quantify the J ¼ 7/2 magnetic anisotropy barrier, 34.80 meV ($280 cm À1), that corresponds with Orbach relaxation via the first excited, M J ¼ AE5/2 doublet. The results demonstrate that dopant sites within solid-state host lattices could offer a viable alternative to rare-earth bulk magnets and high-performance SIMs, where the host matrix can be tailored to impose high symmetry and control lattice induced relaxation effects.
Ivan P. Parkin - One of the best experts on this subject based on the ideXlab platform.
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Nitrides from solid state metathesis reactions: synthesis and mechanistics
Journal of Materials Processing Technology, 1998Co-Authors: Andrew L. Hector, G. Henshaw, A. V. Komarov, Ivan P. ParkinAbstract:Abstract Initiation of a reaction between Lithium Nitride and anhydrous metal halides induces a spontaneous exothermic self-propagating reaction. The products were washed with methanol and analysed as crystalline metal Nitrides (TiN, ZrN, HfN) by X-ray powder diffraction, SEM–EDXA, FT-IR, microanalysis, XPS and magnetic moment measurements. The crystallite size and composition can be controlled in the reaction by the addition of an inert heat sink. Differential Scanning Calorimetry shows exotherms at 200–500°C, whilst thermocouple measurements show a reaction temperature in excess of 1000°C.
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Low-temperature routes to early transition-metal Nitrides
Journal of the Chemical Society Dalton Transactions, 1993Co-Authors: J.c. Fitzmaurice, Andrew L. Hector, Ivan P. ParkinAbstract:Thermal initiation of the reaction of Lithium Nitride with anhydrous transition-metal halides produces crystalline transition-metal Nitrides of various compositions MxNy(M = Y, La, Ti, Zr, Hf, V, Nb, Ta, Cr or Mn)via an exothermic solid-state metathesis reaction. Reaction of anhydrous late transition-metal halides with Lithium Nitride produces the metal (M = Mo, W, Fe, Co, Ni, Cu, Pt, Zn or Cd), dinitrogen and Lithium halide. The metal Nitrides were purified by tetrahydrofuran trituration and characterised by X-ray powder diffraction, scanning electron microscopy, energy dispersive analysis with X-rays, magnetic moment measurements, FTIR spectroscopy and microanalysis.
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Rapid synthesis of TiN, HfN and ZrN from solid-state precursors
Polyhedron, 1993Co-Authors: J.c. Fitzmaurice, Andrew L. Hector, Ivan P. ParkinAbstract:Abstract Microwave or conventional oven initiation of the reaction between Lithium Nitride and anhydrous metal chloride (M = Ti, Zr, Hf) produces metal Nitride NM, dinitrogen and Lithium chloride via a metathesis reaction. The metal Nitrides were characterized by X-ray powder diffraction, SEM, EDAX, IR, magnetic moment measurement and micro-analysis.
J. Frederick W. Mosselmans - One of the best experts on this subject based on the ideXlab platform.
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Single-Ion Magnetism in the Extended Solid-State: Insights from X-ray Absorption and Emission Spectroscopy
Chemical Science, 2020Co-Authors: Myron S. Huzan, M. Fix, Matteo Aramini, Peter Bencok, J. Frederick W. Mosselmans, Shusaku Hayama, Franziska Breitner, Leland B. Gee, Charles J. Titus, Marie-anne ArrioAbstract:Large single-ion magnetic anisotropy is observed in Lithium Nitride doped with iron. The iron sites are two-coordinate, putting iron doped Lithium Nitride amongst a growing number of two coordinate transition metal single-ion magnets (SIMs). Uniquely, the relaxation times to magnetisation reversal are over two orders of magnitude longer in iron doped Lithium Nitride than other 3d-metal SIMs, and comparable with high-performance lanthanide-based SIMs. To understand the origin of these enhanced magnetic properties a detailed characterisation of electronic structure is presented. Access to dopant electronic structure calls for atomic specific techniques, hence a combination of detailed single-crystal X-ray absorption and emission spectroscopies are applied. Together K-edge, L2,3-edge and Kβ X-ray spectroscopies probe local geometry and electronic structure, identifying iron doped Lithium Nitride to be a prototype, solid-state SIM, clean of stoichiometric vacancies where Fe lattice sites are geometrically equivalent. Extended X-ray absorption fine structure and angular dependent single-crystal X-ray absorption near edge spectroscopy measurements determine FeI dopant ions to be linearly coordinated, occupying a D6h symmetry pocket. The dopant engages in strong 3dπ-bonding, resulting in an exceptionally short Fe–N bond length (1.873(7) A) and rigorous linearity. It is proposed that this structure protects dopant sites from Renner–Teller vibronic coupling and pseudo Jahn–Teller distortions, enhancing magnetic properties with respect to molecular-based linear complexes. The Fe ligand field is quantified by L2,3-edge XAS from which the energy reduction of 3dz2 due to strong 4s mixing is deduced. Quantification of magnetic anisotropy barriers in low concentration dopant sites is inhibited by many established methods, including far-infrared and neutron scattering. We deduce variable temperature L3-edge XAS can be applied to quantify the J = 7/2 magnetic anisotropy barrier, 34.80 meV (∼280 cm−1), that corresponds with Orbach relaxation via the first excited, MJ = ±5/2 doublet. The results demonstrate that dopant sites within solid-state host lattices could offer a viable alternative to rare-earth bulk magnets and high-performance SIMs, where the host matrix can be tailored to impose high symmetry and control lattice induced relaxation effects.
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Single-ion magnetism in the extended solid-state: insights from X-ray absorption and emission spectroscopy
Chemical Science, 2020Co-Authors: Myron S. Huzan, M. Fix, Matteo Aramini, Peter Bencok, J. Frederick W. Mosselmans, Shusaku Hayama, Franziska Breitner, Leland Gee, Charles Titus, Marie-anne ArrioAbstract:Large single-ion magnetic anisotropy is observed in Lithium Nitride doped with iron. The iron sites are twocoordinate, putting iron doped Lithium Nitride amongst a growing number of two coordinate transition metal single-ion magnets (SIMs). Uniquely, the relaxation times to magnetisation reversal are over two orders of magnitude longer in iron doped Lithium Nitride than other 3d-metal SIMs, and comparable with high-performance lanthanide-based SIMs. To understand the origin of these enhanced magnetic properties a detailed characterisation of electronic structure is presented. Access to dopant electronic structure calls for atomic specific techniques, hence a combination of detailed single-crystal X-ray absorption and emission spectroscopies are applied. Together K-edge, L 2,3-edge and Kb X-ray spectroscopies probe local geometry and electronic structure, identifying iron doped Lithium Nitride to be a prototype, solid-state SIM, clean of stoichiometric vacancies where Fe lattice sites are geometrically equivalent. Extended X-ray absorption fine structure and angular dependent single-crystal X-ray absorption near edge spectroscopy measurements determine Fe I dopant ions to be linearly coordinated, occupying a D 6h symmetry pocket. The dopant engages in strong 3dp-bonding, resulting in an exceptionally short Fe-N bond length (1.873(7)Å) and rigorous linearity. It is proposed that this structure protects dopant sites from Renner-Teller vibronic coupling and pseudo Jahn-Teller distortions, enhancing magnetic properties with respect to molecular-based linear complexes. The Fe ligand field is quantified by L 2,3-edge XAS from which the energy reduction of 3d z 2 due to strong 4s mixing is deduced. Quantification of magnetic anisotropy barriers in low concentration dopant sites is inhibited by many established methods, including far-infrared and neutron scattering. We deduce variable temperature L 3edge XAS can be applied to quantify the J ¼ 7/2 magnetic anisotropy barrier, 34.80 meV ($280 cm À1), that corresponds with Orbach relaxation via the first excited, M J ¼ AE5/2 doublet. The results demonstrate that dopant sites within solid-state host lattices could offer a viable alternative to rare-earth bulk magnets and high-performance SIMs, where the host matrix can be tailored to impose high symmetry and control lattice induced relaxation effects.