Hydrogen in amorphous Zr<sub>76</sub>Fe<sub>24</sub>

Fries, S. M.; Wagner, H.-G.; Campbell, S. J.; Gonser, U.; Blaes, N.; Steiner, P.

doi:10.1088/0305-4608/15/5/023

Cited by 58 publications

(7 citation statements)

References 20 publications

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“…Most ferrous minerals will order above 4 K, including siderite, green rusts, vivianite, and in some cases, Fe 2+ in clay minerals (191)(192)(193); the lack of ordering is indicative that there is negligible metallic bonding and Fe-Fe interactions (65,71,194). Note that upon careful inspection, the doublets appear to be slightly asymmetrical; this is discussed in greater depth later.…”

Section: Spectral Interpretation Of Sorbed Fe 2+mentioning

confidence: 96%

“…Note that if the peak areas were different, it would likely be due to an unaccounted for Fe 3+ phase contained within the left peak, preferential orientation of the sample, or the Goldanskii-Karyagin effect, where a sample has orientation-dependent f values (8). Asymmetrical doublet peaks have been reported in the literature, and usually arise when a sample is poorly structured, such as in metallic glasses and heterogenic samples, where there are negligible Fe-Fe interactions (70,(194)(195)(196)(197). For sorbed Fe 2+ , the fairly low Fe 2+ uptake as compared to the amount of substrate and lack of crystallinity in a frozen sorbed sample suggest that the sample is indeed heterogenic and poorly ordered.…”

Section: Spectral Interpretation Of Sorbed Fe 2+mentioning

confidence: 99%

“…Using equation 6.1, a simple linear trend is produced, with the slope (CF) being the degree of correlation; it can be seen that if the CF is assumed to be zero, the CS will simply be a constant value (i.e., CS min ). In the literature, both positive and negative CF values have been reported (70,(194)(195)(196)(197), indicating that the CS and QS can relate to one another in fundamentally different ways. Despite our ability to model coupling observed in spectra, it still remains unclear as to why the CS and QS should be coupled, or why the relationship would be linear (197).…”

Section: Qsmentioning

confidence: 99%

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Redox behavior of magnetite in the environment

Gorski¹

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Magnetite (Fe 3 O 4) is a commonly found in the environment and can form via several pathways, including biotic and abiotic reduction of Fe 3+ oxides and the oxidation of Fe 2+ and Fe 0. Despite extensive research, the redox behavior of magnetite is poorly understood. In previous work, the extent and kinetics of contaminant reduction by magnetite varied by several orders of magnitude between studies, two fundamentally different models are used to explain magnetite oxidation (i.e., core-shell diffusion and redox-driven), and reported reduction potentials vary by almost 1 V. In other fields of science (e.g., physics), magnetite stoichiometry (x = Fe 2+ /Fe 3+) is a commonly measured property, however, in environmental studies, the stoichiometry is rarely measured. The stoichiometry of magnetite can range from 0.5 (stoichiometric) to 0 (completely oxidized), with intermediate values (0 < x < 0.5) referred to as nonstoichiometric or partially oxidized magnetite. To determine the relationship between magnetite stoichiometry and contaminant fate, the reduction rates of three substituted nitrobenzenes (ArNO 2) were measured. The kinetic rates varied over five orders of magnitude as the particle stoichiometry increased from x = 0.31 to 0.50. Apparent 15 N kinetic isotope effects (15 N-AKIE) values for ArNO 2 were greater than unity for all magnetite stoichiometries investigated, and indicated that mass transfer processes are not controlling the reaction rate. To determine if the reaction kinetics were redox-driven, magnetite open circuit potentials (E OCP) were measured. E OCP values were linearly related to the stoichiometry, with more stoichiometric magnetite having a lower potential, in good agreement with redox-driven models. The reaction of aqueous Fe 2+ and magnetite was investigated. Similar to previous findings for other Fe 3+ oxides, the formation of a stable sorbed Fe 2+ species was not observed; instead, the sorbed Fe 2+ underwent interfacial electron transfer to form a partially oxidized magnetite phase, which was accompanied by reduction of the viii TABLE OF CONTENTS LIST OF TABLES .

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Section: Spectral Interpretation Of Sorbed Fe 2+mentioning

confidence: 96%

Section: Spectral Interpretation Of Sorbed Fe 2+mentioning

confidence: 99%

Section: Qsmentioning

confidence: 99%

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Redox behavior of magnetite in the environment

Gorski¹

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“…Aubertin et al 1984) and amorphous (see e.g. Fries et al 1984). A good example of the diversity of information available from such studies is provided by the recent work of Wagner et al (1984) on iron doped NbHo•s4 and VD O •7S .…”

Section: Ymentioning

confidence: 99%

An Introduction to Mössbauer Studies of Magnetic Materials

Campbell¹

1984

Aust. J. Phys.

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Aust. J. Phys., 1984,37,429-47 A straightforward introduction to Mossbauer spectroscopy is presented along with a brief background to its discovery over 25 years ago. Several applications of Mossbauer spectroscopy in the study of condensed matter are described. The examples are based on recent investigations of the mixed magnetic AuFe system and amorphous alloys and show how Mossbauer spectroscopy can be used to obtain information on local atomic order, magnetic phases and texture. The diverse range of applications of Mossbauer spectroscopy is outlined, including a brief discussion of its use in topics of current interest in metal physics.

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“…In particular, amorphous Fe 100−x Zr x is known to exhibit Invar characteristics [1] as well as a rich magnetic phase diagram, tunable through changes in the Zr content [2][3][4]. Hydrogen loading of Fe 100−x Zr x has also been shown to significantly influence the magnetic properties [5][6][7], highlighting the importance of subtle changes in the electronic structure for the magnetic properties. Amorphous Fe 100−x Zr x can be grown in the composition range 7 ≤ x ≤ 45 (according to Kiss [8] and Zatroch [9]) and although a ferromagnetic arrangement dominates the magnetic phase diagram, non-collinear structures and spinglass behavior have also been reported.…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of the electrical resistivity and electronic structure of amorphous Fe_100−xZr_xfilms and multilayers

Kapaklis

Pálsson

Vegelius

et al. 2012

J. Phys.: Condens. Matter

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The electrical resistivity of amorphous Fe(100-x)Zr(x) metal alloy films and multilayers has been investigated in a wide temperature and composition range. The overall behavior of the resistivity is consistent with bulk measurements, exhibiting prominent semiconductor-like changes at low temperatures. The transition from positive (metallic) to negative temperature coefficient of resistivity behavior is accompanied by minute changes in magnetoresistance and we can therefore rule out magnetic phase changes as being the cause for the observed changes in the resistivity. Using x-ray absorption and emission spectroscopies we are able to probe the unoccupied and occupied electronic densities of states. The corresponding spectra are found to significantly overlap, as expected for a metallic-like electronic structure and the absence of a band gap. Besides a broadening of the x-ray emission lines expected from an amorphous material, remarkably small differences are observed in the electronic structures when changing the amount of Zr. The resistivity data were modeled and agreement with the Mott variable range hopping model was found, indicating localized electronic states due the disordered structure of the Fe(100-x)Zr(x) alloys.

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Hydrogen in amorphous Zr₇₆Fe₂₄

Cited by 58 publications

References 20 publications

Redox behavior of magnetite in the environment

Redox behavior of magnetite in the environment

An Introduction to Mössbauer Studies of Magnetic Materials

Temperature dependence of the electrical resistivity and electronic structure of amorphous Fe_100−xZr_xfilms and multilayers

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Hydrogen in amorphous Zr76Fe24

Cited by 58 publications

References 20 publications

Redox behavior of magnetite in the environment

Redox behavior of magnetite in the environment

An Introduction to Mössbauer Studies of Magnetic Materials

Temperature dependence of the electrical resistivity and electronic structure of amorphous Fe100−xZrxfilms and multilayers

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Product

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Hydrogen in amorphous Zr₇₆Fe₂₄

Temperature dependence of the electrical resistivity and electronic structure of amorphous Fe_100−xZr_xfilms and multilayers