Étude magnétique des matériaux de type Ln2M12P7 (Ln = Ce, Sm, Gd et Er; M = Co et Fe)

A magnetic study has been undertaken on the substances of formula Ln2M12X7. The magnetic susceptibility and the magnetization have been measured as a function of temperature for a constant field. The magnetic susceptibility measurements have been performed from ambient temperature up to 1000 K. The effective paramagnetic moments were deduced from 1 / χ = f(T) curves, assuming a zero moment on the transition metal atoms. It is shown that these values are in good agreement with the theoretical values calculated for the free ions Ln3+. The saturation moment and the paramagnetic Curie temperature values show an antiferromagnetic behavior for Ce2Co12P7 at low temperature. The magnetic moment of Sm2Co12P7 measured at 4.2 and 78 K under a 2.66 T magnetic field shows a complex magnetic structure at low temperature. Our work on these materials show that the magnetic properties of Ln2M12X7 could be interpreted from previous studies on the phases rare earth transition metal LnM.

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ChemInform Abstract: MODELING CATALYTIC REACTIONS WITH TRANSITION METAL ATOMS. 1. SYNTHESIS AND CHARACTERIZATION OF REACTIVE INTERMEDIATES IN THE NICKEL-ETHYLENE SYSTEM, (C2H4)NNI (WHERE N = 1, 2, OR 3) IN LOW TEMPERATURE MATRICES

Chemischer Informationsdienst ◽

10.1002/chin.197652341 ◽

1976 ◽

Vol 7 (52) ◽

pp. no-no

Author(s):

H. HUBER ◽

G. A. OZIN ◽

W. J. POWER

Keyword(s):

Low Temperature ◽

Transition Metal ◽

Reactive Intermediates ◽

Catalytic Reactions ◽

Synthesis And Characterization ◽

Metal Atoms ◽

Transition Metal Atoms

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Photochemistry of Transition-Metal Atoms: Reactions with Molecular Hydrogen and Methane in Low-Temperature Matrices

Angewandte Chemie International Edition in English ◽

10.1002/anie.198610721 ◽

1986 ◽

Vol 25 (12) ◽

pp. 1072-1085 ◽

Cited By ~ 23

Author(s):

Geoffrey A. Ozin ◽

John G. McCaffrey ◽

J. Mark Parnis

Keyword(s):

Low Temperature ◽

Transition Metal ◽

Molecular Hydrogen ◽

Metal Atoms ◽

Transition Metal Atoms

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Molecular Orbital Studies on the Interaction of Single Transition Metal Atoms with NH3 and H2O Ligands

Zeitschrift für Naturforschung A ◽

10.1515/zna-1981-0407 ◽

1981 ◽

Vol 36 (4) ◽

pp. 347-353

Author(s):

H. Itoh ◽

G. Ertl ◽

A. B. Kunz

Keyword(s):

Transition Metal ◽

Bond Formation ◽

Lone Pair ◽

Metal Atoms ◽

Transition Metal Atoms ◽

Single Transition ◽

Adsorptive Properties ◽

Occupied Orbital ◽

Good Agreement ◽

Mo Theory

The bond formation of 3d-metal atoms (Cr, Fe, Ni, Cu) with NH3 and H2O is investigated by an ab initio MO theory. In the case of NH3, coupling occurs mainly through the HOMO 3a1-levels ≙ (N lone pair), whereas with H2O the main contribution arises from σ-bond formation of the second highest occupied orbital (3a1 ≙O2pz). Results on the bond energies, electron populations and orbital energies are in qualitatively good agreement with experimental data on the adsorptive properties of these molecules on transition metal surfaces

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Modeling catalytic reactions with transition metal atoms. 1. Synthesis and characterization of reactive intermediates in the nickel-ethylene system, (C2H4)nNi (where n = 1, 2, or 3) in low temperature matrices

Journal of the American Chemical Society ◽

10.1021/ja00437a015 ◽

1976 ◽

Vol 98 (21) ◽

pp. 6508-6511 ◽

Cited By ~ 61

Author(s):

H. Huber ◽

G. A. Ozin ◽

W. J. Power

Keyword(s):

Low Temperature ◽

Transition Metal ◽

Reactive Intermediates ◽

Catalytic Reactions ◽

Synthesis And Characterization ◽

Metal Atoms ◽

Transition Metal Atoms

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Local cluster networks and the number of valence states in aluminium–transition metal face-centred icosahedral quasicrystals

Zeitschrift für Kristallographie - Crystalline Materials ◽

10.1515/zkri-2016-2035 ◽

2017 ◽

Vol 232 (7-9) ◽

Cited By ~ 2

Author(s):

Koichi Kitahara ◽

Kaoru Kimura

Keyword(s):

Transition Metal ◽

Local Cluster ◽

Atom Ratio ◽

Metal Atoms ◽

Cluster Networks ◽

Valence States ◽

Transition Metal Atoms ◽

Icosahedral Quasicrystals ◽

The Stability ◽

Good Agreement

AbstractCoordination environments of a special class of clusters which are related to the valence states in aluminium–transition metal face-centred icosahedral quasicrystals were analysed on the basis of the six-dimensional model of Katz and Gratias for the atomic sites and that of Yamamoto for the centres of the clusters. The number of the clusters per atom in the model (≈0.263) is comparable with that of Al–Cu–Ir cubic approximant crystal (≈0.258), and it indicates that the model reasonably represents the distribution of the clusters. We identified all the possible local cluster networks of short distances, which are related to the inter-cluster bonds, and evaluated the number of the valence states by assuming two possible configurations of inter-cluster bonds. The number of the valence states per atom was derived as a function of the fraction of transition-metal atoms, and the value is in good agreement with that expected from the compositions of real quasicrystals. Notably, the number of the part of the valence states which do not depend on the fraction of transition-metal atoms is numerically similar to the electron to atom ratio known as e/a, which is phenomenologically related to the stability of quasicrystals.

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