An investigation of Fe3(PO4)2 — Sarcopside between 1.6K–721 K: Comparision with fayalite

Ericsson, Tore; Khangi, F.A. El

doi:10.1007/bf02400507

Cited by 12 publications

(9 citation statements)

References 3 publications

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“…Furthermore, a smaller site normally gives a lower value of value of CS. Thus, the assignment of the narrow doublet (having the lower CS) to the M1 site in fayalite is in agreement with these rules of thumb, and the same is also true for the Mössbauer assignments in iron sarcopside, Fe 3 (PO 4 ) 2 (Ericsson and Khangi 1988). Using the argument for the centroid shifts in Fe 2 SiS 4 gives that CS(1) should correspond to M1, and CS(2) to M2.…”

Section: Mössbauer Spectra In the Paramagnetic Regionsupporting

confidence: 74%

“…Note that the QS here in the magnetic region is defined as in the equation above. The magnetic field is much higher for the M1 site than for the M2 site, being ≈27 T for M1 and only ≈4 T for M2 at 30 K. In fayalite at 6 K, the corresponding values are ≈32 and ≈12 T, respectively (Ericsson and Khangi 1988).…”

Section: Mössbauer Spectra In the Magnetic Region (30 K-130 K)mentioning

confidence: 90%

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A Mössbauer study of , having the olivine structure: comparison with fayalite and related minerals

Ericsson¹,

Holenyi²,

Amcoff³

1997

J. Phys.: Condens. Matter

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has the olivine structure Pnma with , and at room temperature. The Mössbauer spectrum at 295 K consists of two doublets having centroid shifts (relative to ) and quadrupole splittings for the two metal positions Fe1 (point symmetry ) and Fe2 (point symmetry m) of , and . A point charge calculation for the nearest S octahedra gives the Mössbauer asymmetry parameters and for Fe1 and Fe2 respectively, and for both positions. At approximately 130 K there is an antiferromagnetic transition, and a second transition to a ferromagnetic or ferrimagnetic structure takes place at approximately 30 K. Both magnetic regions show complicated Mössbauer spectra, which require the full Hamiltonian for their analysis. Comparisons are made with Mössbauer results on the related minerals (fayalite), (iron sarcopside), and .

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Section: Mössbauer Spectra In the Paramagnetic Regionsupporting

confidence: 74%

Section: Mössbauer Spectra In the Magnetic Region (30 K-130 K)mentioning

confidence: 90%

A Mössbauer study of , having the olivine structure: comparison with fayalite and related minerals

Ericsson¹,

Holenyi²,

Amcoff³

1997

J. Phys.: Condens. Matter

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“…The corresponding spin-polarized density of states, obtained in self-consistent spin-polarized DFT calculations, projected onto Mn-d, O-p, and P-p states, are shown in Figure 11. It is found that Mn d-states are completely filled in the majority spin channel and completely empty in the minority channel, suggesting the nominal Mn 2+ or d 5 valence state of Mn. The O-p state is found to be mostly occupied, suggesting the nominal O 2− valence state, and P-p state is found to be P 5+ valence state.…”

Section: ■ Resultsmentioning

confidence: 95%

“…The magnetic properties of all members of M 3 (PO 4 ) 2 family excluding the manganese orthophosphate are well-studied. Basically, the transition-metal orthophosphates M 3 (PO 4 ) 2 (M = Fe, Co, Ni, Cu) order antiferromagnetically at low temperatures. − Recently studied chromium orthophosphate Cr 3 (PO 4 ) 2 is represented by two polymorphs. The P 2 1 2 1 2 1 orthorhombic phase α-Cr 3 (PO 4 ) 2 is a weak ferrimagnet with the Curie temperature T C = 29 K. The leading exchange interaction parameters in this phase are characterized by negative Weiss temperature Θ = −96 K, which results in modest frustration ratio |Θ|/ T C ≈ 3 .…”

Section: Introductionmentioning

confidence: 99%

Structure–Property Relationships in α-, β′-, and γ-Modifications of Mn₃(PO₄)₂

et al. 2016

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The manganese orthophosphate, Mn(PO), is characterized by the rich variety of polymorphous modifications, α-, β'-, and γ-phases, crystallized in monoclinic P2/c (P2/n) space group type with unit cell volume ratios of 2:6:1. The crystal structures of these phases are constituted by three-dimensional framework of corner- and edge-sharing [MnO] and [MnO] polyhedra strengthened by [PO] tetrahedra. All compounds experience long-range antiferromagnetic order at Neel temperature T = 21.9 K (α-phase), 12.3 K (β'-phase), and 13.3 K (γ-phase). Additionally, second magnetic phase transition takes place at T* = 10.3 K in β'-phase. The magnetization curves of α- and β'-modifications evidence spin-floplike features at B = 1.9 and 3.7 T, while the γ-Mn(PO) stands out for an extended one-third magnetization plateau stabilized in the range of magnetic field B = 7.5-23.5 T. The first-principles calculations define the main paths of superexchange interaction between Mn spins in these polymorphs. The spin model for α-phase is found to be characterized by collection of uniform and alternating chains, which are coupled in all three directions. The strongest magnetic exchange interaction in γ-phase emphasizes the trimer units, which make chains that are in turn weakly coupled to each other. The spin model of β'-phase turns out to be more complex compared to α- or γ-phase. It shows complex chain structures involving exchange interactions between Mn2 (Mn2', Mn2″) and Mn3 (Mn3', Mn3″). These chains interact through exchanges involving Mn1 (Mn1', Mn1″) spins.

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“…The absence of Fe(III) in the weak acid extract indicated that the transformation product was also not green-rust (GR), a mixed Fe(II)/Fe(III) phase, even though the fit-derived Mö ssbauer parameters at 77 K matched well with GR-like compounds (e.g., Ona-Nguema et al, 2002;Kukkadapu et al, 2004). The Mö ssbauer parameters of the biogenic Fe(II) phase were also not consistent with fayalite [Fe(II) 2 SiO 4 ; e.g., Ericsson and Khangi, 1988] that magnetically orders at 77 K, or greenalite [Fe(II) 2.3 Fe(III) 0.5 Si 2.2 O 5 (OH) 3.3 ] (e.g., Ballet and Coey, 1978). The Mö ssbauer parameters and solubility behavior of the biogenic Fe phase also did not agree with Fe(OH) 2 (Koch, 1998).…”

Section: The Biotransformation Product Of Goethitementioning

confidence: 88%

Reductive biotransformation of Fe in shale–limestone saprolite containing Fe(III) oxides and Fe(II)/Fe(III) phyllosilicates

Kukkadapu

Zachara

Fredrickson

et al. 2006

Geochimica et Cosmochimica Acta

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A <2.0-mm fraction of a mineralogically complex subsurface sediment containing goethite and Fe(II)/Fe(III) phyllosilicates was incubated with Shewanella putrefaciens (strain CN32) and lactate at circumneutral pH under anoxic conditions to investigate electron acceptor preference and the nature of the resulting biogenic Fe(II) fraction. Anthraquinone-2,6-disulfonate (AQDS), an electron shuttle, was included in select treatments to enhance bioreduction and subsequent biomineralization. The sediment was highly aggregated and contained two distinct clast populations: (i) a highly weathered one with ''sponge-like'' internal porosity, large mineral crystallites, and Fecontaining micas, and (ii) a dense, compact one with fine-textured Fe-containing illite and nano-sized goethite, as revealed by various forms of electron microscopic analyses. Approximately 10-15% of the Fe(III) TOT was bioreduced by CN32 over 60 d in media without AQDS, whereas 24% and 35% of the Fe(III) TOT was bioreduced by CN32 after 40 and 95 d in media with AQDS. Little or no Fe 2+ , Mn, Si, Al, and Mg were evident in aqueous filtrates after reductive incubation. Mö ssbauer measurements on the bioreduced sediments indicated that both goethite and phyllosilicate Fe(III) were partly reduced without bacterial preference. Goethite was more extensively reduced in the presence of AQDS whereas phyllosilicate Fe(III) reduction was not influenced by AQDS. Biogenic Fe(II) resulting from phyllosilicate Fe(III) reduction remained in a layer-silicate environment that displayed enhanced solubility in weak acid. The mineralogic nature of the goethite biotransformation product was not determined. Chemical and cryogenic Mö ssbauer measurements, however, indicated that the transformation product was not siderite, green rust, magnetite, Fe(OH) 2 , or Fe(II) adsorbed on phyllosilicate or bacterial surfaces. Several lines of evidence suggested that biogenic Fe(II) existed as surface associated phase on the residual goethite, and/or as a Fe(II)-Al coprecipitate. Sediment aggregation and mineral physical and/or chemical factors were demonstrated to play a major role on the nature and location of the biotransformation reaction and its products.

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An investigation of Fe3(PO4)2 — Sarcopside between 1.6K–721 K: Comparision with fayalite

Cited by 12 publications

References 3 publications

A Mössbauer study of , having the olivine structure: comparison with fayalite and related minerals

A Mössbauer study of , having the olivine structure: comparison with fayalite and related minerals

Structure–Property Relationships in α-, β′-, and γ-Modifications of Mn₃(PO₄)₂

Reductive biotransformation of Fe in shale–limestone saprolite containing Fe(III) oxides and Fe(II)/Fe(III) phyllosilicates

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An investigation of Fe3(PO4)2 — Sarcopside between 1.6K–721 K: Comparision with fayalite

Cited by 12 publications

References 3 publications

A Mössbauer study of , having the olivine structure: comparison with fayalite and related minerals

A Mössbauer study of , having the olivine structure: comparison with fayalite and related minerals

Structure–Property Relationships in α-, β′-, and γ-Modifications of Mn3(PO4)2

Reductive biotransformation of Fe in shale–limestone saprolite containing Fe(III) oxides and Fe(II)/Fe(III) phyllosilicates

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Structure–Property Relationships in α-, β′-, and γ-Modifications of Mn₃(PO₄)₂