Low temperature magnetism and Mössbauer spectroscopy study from natural goethite

Berquó, Thelma S.; Imbernon, Rosely Aparecida Liguori; Blot, Alain; Franco, Diogo; Toledo, Maria Cristina Motta de; Partiti, C. S. M.

doi:10.1007/s00269-007-0147-9

Cited by 22 publications

(14 citation statements)

References 30 publications

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“…6. However, similar low-temperature upturns in χ have been reported in other near-stoichiometric goethite, including one from Gangaol, Burkina Faso, 39 for which T N = 380 K, which implies that it is an intrinsic effect; and further evidence below leads us to conclude that this is not simply a paramagnetic relaxation signal.…”

Section: Ac Susceptibilitysupporting

confidence: 80%

“…60-70 K, whose functional dependence followed a Vogel-Fulcher law, typical of ordering in interacting systems. 39,40 There are alternative explanations: in particular, the observation of frequency-dependent χ (T) peaks could be taken as a sign of superferromagnetism, as recently discussed in hematite and Fe-Ag fims. 5,6,54 The two interpretations, cluster ordering and superferromagnetism, are closely related, differing in the length scale of the interacting coherently magnetized regions: clusters and particles, respectively.…”

Section: Discussionmentioning

confidence: 99%

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Intrinsic magnetic relaxation in goethite

et al. 2012

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The intrinsic magnetic relaxation properties of goethite are elucidated via a comparative study of the magnetism of a stoichiometric and a nonstoichiometric sample, α-FeOOH and α-Fe 0.92 0.08 O 0.76 OH 0.24 , where denotes a vacancy site. It is proposed that both goethite samples exhibit "mode superparamagnetism" at low temperatures, wherein the iron moments undergo thermally induced fluctuations over an energy barrier separating two closely related geometrical arrangements for the sublattice spins. This is an intrinsic relaxation mechanism that was previously predicted from magnetic structure refinements, which we have identified here in ac susceptibility and thermal decay of remanence data. An additional magnetic relaxation mode occurs in the nonstoichiometric goethite. This mode is characterized by relatively slow fluctuations, observable on the microsecond timescale of muon spin relaxation experiments, but not on the fast timescale of Mössbauer spectroscopy, and appearing in ac susceptibility and dc magnetization data as blocking transitions in the range 70 to 100 K. These data are best described as the result of "cluster ordering": the formation and relaxation of magnetic clusters in the disturbed environment of the nonstoichiometric lattice.

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Section: Ac Susceptibilitysupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Intrinsic magnetic relaxation in goethite

et al. 2012

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“…According to Takano et al This value is significantly reduced when compared with the typical B HF value of goethite, which is 38T [36]. Structural defects, like vacancies and/or isomorphic substitution, and also small particle size are the main contributors to reduced B HF values [37]. …”

Section: Mössbauer Spectroscopymentioning

confidence: 97%

Study of arsenopyrite weathering products in mine wastes from abandoned tungsten and tin exploitations

Murciego

Álvarez‐Ayuso

Pellitero

et al. 2011

Journal of Hazardous Materials

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“…No other magnetic oxides (e.g., ferrihydrite) were detected. The appearance of goethite in spectra collected at T < 20 K but not at 300 K is ascribed to a significant fraction of nano‐size goethite with particle sizes below 50 nm (Berquó et al, 2007; Guyodo et al, 2006; van der Zee et al, 2003). The hematite spectra indicated that the hematite was fined grained (<1,000 nm) but without a significant nano‐sized particle fraction.…”

Section: Results and Interpretationsmentioning

confidence: 99%

Dust Deposited on Snow Cover in the San Juan Mountains, Colorado, 2011–2016: Compositional Variability Bearing on Snow‐Melt Effects

et al. 2020

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Light‐absorbing particles in atmospheric dust deposited on snow cover (dust‐on‐snow, DOS) diminish albedo and accelerate the timing and rate of snow melt. Identification of these particles and their effects is relevant to snow‐radiation modeling and water‐resource management. Laboratory‐measured reflectance of DOS samples from the San Juan Mountains (USA) were compared with DOS mass loading, particle sizes, iron mineralogy, carbonaceous matter type and content, and chemical compositions. Samples were collected each spring for water years 2011–2016, when individual dust layers had merged into one (all layers merged) at the snow surface. Average reflectance values of the six samples were 0.2153 (sd, 0.0331) across the visible wavelength region (0.4–0.7 μm) and 0.3570 (sd, 0.0498) over the full‐measurement range (0.4–2.50 μm). Reflectance values correlated inversely to concentrations of ferric oxide, organic carbon (1.4–10 wt.%), magnetite (0.05–0.13 wt.%), and silt (PM63‐3.9; median grain sizes averaged 21.4 μm) but lacked correspondence to total iron and PM10 contents. Measurements of reflectance and Mössbauer spectra and magnetic properties indicated that microcrystalline hematite and nano‐size goethite were primarily responsible for diminished visible reflectance. Positive correlations between organic carbon and metals attributed to fossil‐fuel combustion, with observations from electron microscopy, indicated that some carbonaceous matter occurred as black carbon. Magnetite was a surrogate for related light‐absorbing minerals, dark rock particles, and contaminants. Similar analyses of DOS from other areas would help evaluate the influences of varied dust sources, wind‐storm patterns, and anthropogenic inputs on snow melt and water resources in and beyond the Colorado River Basin.

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Low temperature magnetism and Mössbauer spectroscopy study from natural goethite

Cited by 22 publications

References 30 publications

Intrinsic magnetic relaxation in goethite

Intrinsic magnetic relaxation in goethite

Study of arsenopyrite weathering products in mine wastes from abandoned tungsten and tin exploitations

Dust Deposited on Snow Cover in the San Juan Mountains, Colorado, 2011–2016: Compositional Variability Bearing on Snow‐Melt Effects

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