Vacancy ordering in Fe7Se8-Fe7S8 solid solutions studied by Mössbauer, X-ray and magnetization techniques

Ericsson, Tore; Amcoff, Örjan; Nordblad, Per

doi:10.1007/bf02069165

Cited by 12 publications

(7 citation statements)

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“…The 2S1 and 2S2 sextets were assigned to the sites without vacancies around the Fe atom, while the 2S3 and 2S4 sextets were assigned to the sites with vacancies in different configurations with respect to the Fe atom. For 2S3, there are two vacancies in trans-configuration to each other above and below Fe, and for 2S4, there are two vacancies in trans-configuration above the Fe atom and one directly below. , Pyrite was fitted with one doublet (2D1), and the fitted parameters (CS = 0.34 mm/s, QS = 0.62 mm/s, Table S3) were within the range reported in the literature (CS = 0.28–0.40 mm/s, QS = 0.56–0.65 mm/s). Mössbauer analysis of the Falconbridge pyrrhotite revealed the presence of two more doublets, 2D2 (CS = 1.14 mm/s, QS = 2.62 mm/s, Table S3) and 3D3 (CS = 0.45 mm/s, QS = 1.13 mm/s, Table S3), assigned to Fe(II) and Fe(III) in octahedral coordination in phyllosilicates (clinochlore and muscovite), respectively.…”

Section: Resultssupporting

confidence: 67%

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Formation of Fe(III) (Hydr)oxides from Fe(II) Sulfides: Implications for Akaganeite Detection on Mars

Peretyazhko

Ming

Morris

et al. 2021

ACS Earth Space Chem.

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Akaganeite on Mars could form from Fe(II) sulfides, but formation conditions remain unconstrained. We investigated akageneite formation by oxidative alteration of natural pyrrhotites exposed to HCl and oxidation–hydrolysis of Fe(II) HCl-leached from pyrrhotites at initial pH0 1.5, 2, 3, and 4. X-ray diffraction and Mössbauer analyses revealed the formation of poorly crystallized akageneite in oxidative alteration experiments. Air exposure of the HCl-reacted dry pyrrhotites led to an increase in akageneite formation and precipitation of Fe(II) hydrated sulfates, goethite, and hydronium jarosite. Iron(II) oxidation–hydrolysis was sensitive to Si dissolved from phyllosilicates in one pyrrhotite sample. Akaganeite and goethite formed at pH0 1.5 and 2 with akageneite more abundant at a dissolved Si/Fe ratio of 0.08 and goethite more abundant at a Si/Fe of 0.01. Akaganeite formed together with hematite, ferrihydrite, and goethite at pH0 3, and formation was suppressed at pH0 4. Well-crystallized akageneite precipitated at pH0 1.5, while akaganeite of poorer crystallinity formed at pH0 2 and 3. Akageneite on Mars could form from sulfides by both mechanisms during late diagenetic events triggered by interactions of acidic Cl-bearing groundwater with Fe(II) sulfides. Akaganeite in Yellowknife Bay, Gale Crater, could have formed by Fe(II) oxidation–hydrolysis either as a sole Fe(III) (hydr)oxide at pH < 2 or along with ferrihydrite and hematite at 2 < pH < 4 under Si-enriched conditions. Akaganeite formation at the Vera Rubin ridge, Gale Crater, could have occurred through oxidative alteration of sulfides in Cl-bearing pH 1.2–1.5 solutions. The presence of well-crystallized akageneite in the Rock Hall site at the Vera Rubin ridge indicates that Fe(II) oxidation–hydrolysis contributed to akageneite formation.

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Section: Resultssupporting

confidence: 67%

“…Four Fe(II) pyrrhotite sextets correspond to different distributions of vacancies around Fe sites − (Figure , Table S3). The 2S1 and 2S2 sextets were assigned to the sites without vacancies around the Fe atom, while the 2S3 and 2S4 sextets were assigned to the sites with vacancies in different configurations with respect to the Fe atom.…”

Section: Resultsmentioning

confidence: 99%

Formation of Fe(III) (Hydr)oxides from Fe(II) Sulfides: Implications for Akaganeite Detection on Mars

Peretyazhko

Ming

Morris

et al. 2021

ACS Earth Space Chem.

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“…The compositions will in the following be denoted: Fe, 5% Co, 10% Ni, etc. The exact synthesis procedure has been explained elsewhere [4]. X-ray diffraction showed that all product samples contained a few wt.% of iron sulphide (Fe 1-x S) beside the olivine phase.…”

Section: Samplesmentioning

confidence: 99%

“…It was shown that the MS signals from iron at M1 and M2 were of closely equal strength and did not vary with temperature, thus the two positions have nearly equal f-factors. In a second publication [4] we studied (Fe, Me) 2 SiS 4 Me Co or Ni, mainly at room temperature, to determine cation preferential occupations. It was then proposed, mainly from magnetisation and cation preference arguments on Fe 2 SiS 4 in comparison with Fe 2 GeS 4 , that iron at M2 gives a lower CS value than iron at Ml, however, without giving fully convincing arguments.…”

Section: 22mentioning

confidence: 99%

Magnetisation and Mössbauer studies of (Fe_1-xMe_x)₂SiS₄,x≤ 0.25 andMe= Co or Ni

1999

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In the large extra dimensional ADD scenario, Z bosons undergo a one-loop decay into a photon and Kaluza-Klein towers of gravitons/gravi-scalars. We calculate such a decay width, extending previous arguments about the general form of the fourdimensional on-shell amplitude. The amplitudes calculated are relevant to processes in other extra dimensional models where the Standard Model fields are confined to a 4-brane.

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“…The presence of vacancies in every second Fe layer leads to incomplete compensation of magnetic moments and to a ferrimagnetic order which enters below the Neel temperature of about 590 K [1,2]. The magnetic properties of Fe 7 X 8 are strongly influenced by substitutions in both the Fe [3,4] and chalcogen sublattices [5]. The replacement of iron in Fe 7¡y M y X 8 (X = S, Se) by other 3d metal (M = Ti, Co) atoms in cation layers is found to be non-random and dramatically affects the magnetic behavior [4].…”

Section: Introductionmentioning

confidence: 99%

Crystal Structure and Magnetic Properties of Pyrrhotite-Type Compounds Fe_7-yV_yS₈

et al. 2018

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The pyrrhotite-type compounds Fe7¡yVyS8 have been synthesized and studied by means of the X-ray diffraction and magnetization measurements in order to reveal how the substitution of V for Fe affects the crystal structure, phase transition and magnetic properties. The growth of the V content in Fe7¡yVyS8 results in changes of the crystal structure and leads to a sharp decrease in the resultant magnetization, non-monotonous change of the coercive field and reduction of the magnetic ordering temperature. Unlike ferrimagnetic ordering in pyrrhotite Fe7S8 the compound V7S8 is observed to exhibit a Pauli-paramagnetic behaviour.

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Vacancy ordering in Fe7Se8-Fe7S8 solid solutions studied by Mössbauer, X-ray and magnetization techniques

Cited by 12 publications

References 5 publications

Formation of Fe(III) (Hydr)oxides from Fe(II) Sulfides: Implications for Akaganeite Detection on Mars

Formation of Fe(III) (Hydr)oxides from Fe(II) Sulfides: Implications for Akaganeite Detection on Mars

Magnetisation and Mössbauer studies of (Fe_1-xMe_x)₂SiS₄,x≤ 0.25 andMe= Co or Ni

Crystal Structure and Magnetic Properties of Pyrrhotite-Type Compounds Fe_7-yV_yS₈

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Vacancy ordering in Fe7Se8-Fe7S8 solid solutions studied by Mössbauer, X-ray and magnetization techniques

Cited by 12 publications

References 5 publications

Formation of Fe(III) (Hydr)oxides from Fe(II) Sulfides: Implications for Akaganeite Detection on Mars

Formation of Fe(III) (Hydr)oxides from Fe(II) Sulfides: Implications for Akaganeite Detection on Mars

Magnetisation and Mössbauer studies of (Fe1-xMex)2SiS4,x≤ 0.25 andMe= Co or Ni

Crystal Structure and Magnetic Properties of Pyrrhotite-Type Compounds Fe7-yVyS8

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Magnetisation and Mössbauer studies of (Fe_1-xMe_x)₂SiS₄,x≤ 0.25 andMe= Co or Ni

Crystal Structure and Magnetic Properties of Pyrrhotite-Type Compounds Fe_7-yV_yS₈