Magnetic properties and site occupancy of iron in nontronite

AbstractThe magnetic susceptibilities of seven different nontronites in their natural oxidation states were measured between 5 and 100 K. Results revealed that the magnetic exchange interaction in all samples was antiferromagnetic, except no clear minimum occurred at the Néel temperature. Possible explanations for this phenomenon which are discussed include magnetic dilution due to isomorphous substitution, and antiferromagnetic frustration due to either non-centrosymmetric distribution of octahedral Fe3+ or tetrahedral Fe3+ substitution. A computer simulation model was developed to demonstrate the effects of these variables on long-range magnetic ordering. Magnetic dilution and tetrahedral Fe3+ content could explain the anomalous antiferromagnetic behaviour in some, but not all, samples. The non-centrosymmetric model is the only one which explains the behaviour of all samples. In this model, at least 13% of the octahedral Fe3+ would occupy trans-dihydroxide sites, with the balance in cis sites. Magnetic frustration occurs because two Fe3+ neighbours of a third Fe3+ ion are also neighbours to each other, making the simultaneous satisfaction of all antiferromagnetic exchange interactions impossible.

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Metal Complexes with Nitronyl Nitroxide Substituted Phenolate Ligands Providing New Magnetic Exchange Interaction Pathways − Synthesis, Structures, Magnetic Dilution Studies, and Ab Initio Calculations

European Journal of Inorganic Chemistry ◽

10.1002/1099-0682(200109)2001:10<2569::aid-ejic2569>3.0.co;2-3 ◽

2001 ◽

Vol 2001 (10) ◽

pp. 2569-2586 ◽

Cited By ~ 28

Author(s):

Ulrich Schatzschneider ◽

Thomas Weyhermüller ◽

Eva Rentschler

Keyword(s):

Ab Initio Calculations ◽

Metal Complexes ◽

Ab Initio ◽

Exchange Interaction ◽

Nitronyl Nitroxide ◽

Magnetic Exchange Interaction ◽

Magnetic Exchange ◽

Magnetic Dilution ◽

Phenolate Ligands

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Antiferromagnetic exchange and long-range magnetic ordering in supramolecular networks constructed of hexacyanido-bridged LnIII(3-pyridone)–CrIII (Ln = Gd, Tb) chains

CrystEngComm ◽

10.1039/c7ce02077e ◽

2018 ◽

Vol 20 (9) ◽

pp. 1271-1281 ◽

Cited By ~ 5

Author(s):

Szymon Chorazy ◽

Michał Rams ◽

Maciej Wyczesany ◽

Koji Nakabayashi ◽

Shin-ichi Ohkoshi ◽

...

Keyword(s):

Phase Transitions ◽

Long Range ◽

Magnetic Phase ◽

Magnetic Ordering ◽

Exchange Interactions ◽

Magnetic Phase Transitions ◽

Antiferromagnetic Exchange ◽

Supramolecular Networks ◽

Calorimetric Studies

Exchange interactions and magnetic phase transitions are observed in novel cyanido-bridged lanthanide(iii)–chromium(iii) chains as proved by magnetic and calorimetric studies.

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ChemInform Abstract: MAGNETIC EXCHANGE INTERACTIONS IN BINUCLEAR TRANSITION-METAL COMPLEXES. 20. VARIATION IN MAGNETIC EXCHANGE INTERACTION FOR A SERIES OF METAL(II) COMPLEXES OF A BINUCLEATING LIGAND

Chemischer Informationsdienst ◽

10.1002/chin.198002059 ◽

1980 ◽

Vol 11 (2) ◽

Author(s):

S. L. LAMBERT ◽

D. N. HENDRICKSON

Keyword(s):

Transition Metal ◽

Metal Complexes ◽

Exchange Interaction ◽

Transition Metal Complexes ◽

Exchange Interactions ◽

Magnetic Exchange Interaction ◽

Magnetic Exchange

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Magnetic exchange interactions in binuclear transition-metal complexes. 20. Variation in magnetic exchange interaction for a series of metal(II) complexes of a binucleating ligand

Inorganic Chemistry ◽

10.1021/ic50200a009 ◽

1979 ◽

Vol 18 (10) ◽

pp. 2683-2686 ◽

Cited By ~ 75

Author(s):

Susan L. Lambert ◽

David N. Hendrickson

Keyword(s):

Transition Metal ◽

Metal Complexes ◽

Exchange Interaction ◽

Transition Metal Complexes ◽

Exchange Interactions ◽

Magnetic Exchange Interaction ◽

Magnetic Exchange

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Magnetic Properties of Ions Implanted in Glass; Fe in SiO2

MRS Proceedings ◽

10.1557/proc-45-59 ◽

1985 ◽

Vol 45 ◽

Cited By ~ 2

Author(s):

R.A. Weeks ◽

M.C. Silva ◽

G. Kordas ◽

D.L. Kinser ◽

J. Martinelli ◽

...

Keyword(s):

Spectral Component ◽

Maximum Amplitude ◽

Magnetic Ordering ◽

Exchange Interactions ◽

Sample Surface ◽

Orientation Dependence ◽

Ion Scattering ◽

Ion Distribution ◽

Magnetic Exchange ◽

Fe Ions

ABSTRACTSilica glass platelets have been implanted with Fe(+) ions, 125 KeV and 10⋀-5 A to doses of 10⋀14 cm⋀-2, 10⋀15 cm⋀-2, 10⋀16 cm⋀-2 and 5 x 10⋀16 cm⋀-2. Ion scattering measurements show that the peak of the Fe ion distribution is ~95 nm below the sample surface, approximately Gaussian, with a width at half maximum amplitude of 100 nm. The intensity of a component in the EPR spectra of implanted samples with a width of 300 gauss and an approximately isotropic shape increases with increasing dose. The increase, proportional to dose for doses <⋀16 cm⋀-2, is larger for doses ≥10⋀16 cm⋀-2. In addition for doses ≥10⋀16 cm⋀-2, the component is orientation dependent. Subsequent heat treatments in air at 700° and 800° C alter the shape, intensity, and orientation dependence of the component. The spectral component in as-implanted samples is attributed to paramagnetic states of Fe ions. The threshold for magnetic exchange interactions and consequently long range magnetic ordering at ~300K occurs at a dose ≥10⋀16 cm⋀-2. Data on effects of thermal treatments on intensities and shapes are interpreted in terms of changing chemical composition of precipitating-particles.

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Structures and Physical Properties of Ternary Antimonides RE3MSb5 (M = Zr, Hf), U3MSb5 (M = Zr, Hf, Nb), and YbCrSb3

MRS Proceedings ◽

10.1557/proc-848-ff2.6 ◽

2004 ◽

Vol 848 ◽

Author(s):

Andriy V. Tkachuk ◽

Shane J. Crerar ◽

Xing Wu ◽

Craig P. T. Muirhead ◽

Laura Deakin ◽

...

Keyword(s):

Magnetic Properties ◽

Electrical Resistivity ◽

Magnetic Susceptibility ◽

Rare Earth ◽

Magnetic Ordering ◽

Exchange Interactions ◽

Electronic Transitions ◽

Magnetic Exchange ◽

Electrical And Magnetic Properties ◽

Fertile Ground

ABSTRACTTernary rare-earth transition-metal antimonides RExMySbz have provided fertile ground for discovering materials with varied electrical and magnetic properties such as superconductivity and ferromagnetism. The properties of two important classes of these compounds, RE3TiSb5 and RECrSb3, have been previously investigated. These studies have now been extended to RE3MSb5 (M = Zr, Hf), which show anomalies in their resistivity curves suggestive of electronic transitions, and YbCrSb3, which undergoes long-range magnetic ordering at 285 K, the highest Tc observed so far of all RECrSb3 members. Strong magnetic exchange interactions develop through coupling of f and d electrons in these compounds. The substitution of uranium for rare earth in RE3MSb5 results in the compounds U3MSb5 (M = Zr, Hf, Nb), which also display prominent transitions in their electrical resistivity and magnetic susceptibility curves.

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Solvent-tuned magnetic exchange interactions in Dy2 systems ligated by a μ-phenolato heptadentate Schiff base

RSC Advances ◽

10.1039/c9ra08754k ◽

2019 ◽

Vol 9 (68) ◽

pp. 39640-39648 ◽

Cited By ~ 4

Author(s):

Zhijie Jiang ◽

Lin Sun ◽

Min Li ◽

Haipeng Wu ◽

Zhengqiang Xia ◽

...

Keyword(s):

Schiff Base ◽

Exchange Interaction ◽

Magnetic Relaxation ◽

Exchange Interactions ◽

Relaxation Dynamics ◽

Magnetic Exchange Interaction ◽

Magnetic Exchange

Solvent-tuning changes the magnetic exchange interaction and results in different magnetic relaxation dynamics in Dy2 systems ligated by a μ-phenolato heptadentate Schiff base.

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Effects of iron oxidation states on the surface and structural properties of smectites

Pure and Applied Chemistry ◽

10.1351/pac200274112145 ◽

2002 ◽

Vol 74 (11) ◽

pp. 2145-2158 ◽

Cited By ~ 60

Author(s):

J. W. Stucki ◽

K. Lee ◽

L. Zhang ◽

R. A. Larson

Keyword(s):

Surface Chemistry ◽

Clay Minerals ◽

Dominant Role ◽

Surface Acidity ◽

Iron Oxidation ◽

Site Occupancy ◽

Chemical Properties ◽

Exchange Interactions ◽

Magnetic Exchange ◽

Fe Reduction

The oxidation state of iron (Fe) in the crystal structure of smectite clay minerals profoundly alters their physical-chemical properties. Among the properties affected are layer charge, cation exchange and fixation capacity, swelling in water, particle size, specific surface area, layer stacking order, magnetic exchange interactions, octahedral site occupancy, surface acidity, and reduction potential. Also affected is the surface chemistry of the clay, which alters clay–water and clay–organic interaction mechanisms. Rates and extents of degradation of pesticides are increased in the presence of reduced smectites compared to oxidized and reduced-reoxidized counterparts. A hypothesis regarding the mechanism for Fe reduction in clay minerals was first developed in 1963, and subsequent modifications have been proposed periodically through the present time. Recent studies clearly reveal that the process of Fe reduction involves more than the mere transfer of an electron to octahedral Fe(III) in the clay crystal. Ancillary reactions occur that produce significant structural modifications, some of which are reversible and others of which are not. Such changes in the crystal-chemical environment of structural Fe are thought to play a dominant role in altering the clay surface chemistry.

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