Mössbauer studies of the solid solutions of synthetic hureaulite, [FexMn5−x]PO4H]2[PO4]2[H2O]4

Moreira, L. F.; Domingues, P.H.; Mattievich, E.

doi:10.1016/0304-8853(94)90313-1

Cited by 8 publications

(13 citation statements)

References 2 publications

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“…It shows four well-separated absorption lines which can be evaluated by two or three doublets for Fe 2þ ; there is no evidence for ferric iron in the sample. While a twodoublet analysis yields acceptable fit, but cannot reproduce a slight asymmetry and exhibits some misfit of the two innermost lines, a three-doublet fit is significantly better (reduced w 2 of 1.14 as compared to 3.48 for two doublets), and consistent with the findings of Moreira et al (1994) and Bustamente et al (2005). The 57 Fe-Mössbauer parameters are listed in Table 5 and are in line with the observations of the literature.…”

Section: ) Mössbauer Spectroscopysupporting

confidence: 83%

“…A more recent infrared study on a polycrystalline sample of hureaulite was reported by Frost & Erickson (2005); however, the sample was not well characterized (i.e., no chemical or crystallographic data were provided) and only a general assignment of the active bands was reported, without any crystallographic implication. A few Mössbauer studies on hureaulite-type materials have so far been published, the first dates back to Moreira et al (1994), who investigated nine synthetic samples across a complete solid-solution series (Fe x Mn 5Àx )(PO 4 H) 2 (PO 4 ) 2 (H 2 O) 4 , determining the site occupation and range of hyperfine parameters. For the pure end-member composition (i.e., x ¼ 5) they assigned the doublet with the lowest area fraction to the M(1) site, in accordance with the site occupation ratio of 1:2:2 for M(1):M(2):M(3).…”

Section: Special Issue Dedicated To Thomas Armbrustermentioning

confidence: 99%

“…Conversely, the doublet with the largest quadrupole splitting was ascribed to the M(3) site, which has the most distorted oxygen-atom environment of all the three sites. From changes in site occupation numbers of Fe 2þ across the solid solution, Moreira et al (1994) found that Mn 2þ preferentially populates the most distorted M(3) site. Later on, Bustamente et al 2005reinvestigated the Mössbauer spectrum of the synthetic ferrous endmember; they used the site assignment proposed by Moreira et al (1994), giving supporting arguments for it from calculation of polyhedral distortion parameters derived from singlecrystal X-ray diffraction on the material.…”

Section: Special Issue Dedicated To Thomas Armbrustermentioning

confidence: 99%

“…From changes in site occupation numbers of Fe 2þ across the solid solution, Moreira et al (1994) found that Mn 2þ preferentially populates the most distorted M(3) site. Later on, Bustamente et al 2005reinvestigated the Mössbauer spectrum of the synthetic ferrous endmember; they used the site assignment proposed by Moreira et al (1994), giving supporting arguments for it from calculation of polyhedral distortion parameters derived from singlecrystal X-ray diffraction on the material. Dyar et al (2014) compiled a large number of Mössbauer data for iron phosphates, including hureaulite, which contains Fe 2þ only in two positions, namely the M(2) and the M(3) ones.…”

Section: Special Issue Dedicated To Thomas Armbrustermentioning

confidence: 99%

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Single-crystal neutron diffraction and Mössbauer spectroscopic study of hureaulite, (Mn,Fe)5(PO4)2 (HPO4)2 (H2O)4

Gatta¹,

Redhammer²,

Vignola³

et al. 2016

ejm

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The crystal chemistry of hureaulite from the Jocão (Cigana) pegmatite, Conselheiro Pena, Doce Valley, Minas Gerais (Brazil), was investigated by electron microprobe analysis in wavelength-dispersive mode, single-crystal Laue (at 293 K) and monochromatic neutron diffraction (at 2.3 K), and 57 Fe-Mössbauer spectroscopy [ M(1),M(2),M(3) (Mn 2þ 3.61 Fe 2þ 1.21 Ca 0.11 Mg 0.03) P ¼4.96 (P(2) PO 4) 2 (H 1.04 P(1) PO 4) 2 (H 2 O) 3.92 , Z ¼ 4, a ¼ 17.603(6), b ¼ 9.087(2), c ¼ 9.404(4) Å , b ¼ 96.66(4) , and V ¼ 1494.1(9) Å 3 at 293 K, space group C2/c]. The neutron refinements confirm the general structure model previously reported, showing that five independent H sites (with full site occupancy) occur in the hureaulite structure, one of them as member of the unique hydroxyl group (i.e., O(1)-H(1)) and the other four belonging to two independent H 2 O molecules (i.e., H(2)-O(9)-H(3) and H(4)-O(10)-H(5)). The hydroxyl group is the vertex of one of the two independent P-tetrahedra (i.e., HOPO 3), whereas the two H 2 O molecules are the vertices of the (Mn,Fe)-octahedra. No zeolitic H 2 O occurs in hureaulite structure. The complex hydrogen bonding scheme in hureaulite is now well defined, with five hydrogen bonds energetically favorable. The element distribution among the octahedral sites, deduced on the basis of the neutron structure refinements, shows that the highest fraction of Fe populates the M(2) site ($36%), whereas lower fractions are observed at M(1) and M(3) (i.e., $13-15 and $11-12%, respectively). The 57 Fe Mössbauer spectrum of hureaulite confirms the absence of ferric iron in the sample. The spectrum shows four well-separated absorption lines which are best fitted with three doublets. The well-resolved doublet (with the largest quadrupole splitting) is here assigned to the M(3) site, in line with the pronounced preference of Mn 2þ for the M(3) site as shown by the neutron structure refinements. The two innermost doublets have almost identical isomer shifts, though with slightly different quadrupole splitting values; the smaller quadrupole splitting value is assigned to the M(2) site, which is expected to have a slightly lower polyhedral distortion than the M(1) site, according to the experimental findings based on the neutron refinements.

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Section: ) Mössbauer Spectroscopysupporting

confidence: 83%

Section: Special Issue Dedicated To Thomas Armbrustermentioning

confidence: 99%

Section: Special Issue Dedicated To Thomas Armbrustermentioning

confidence: 99%

Section: Special Issue Dedicated To Thomas Armbrustermentioning

confidence: 99%

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Single-crystal neutron diffraction and Mössbauer spectroscopic study of hureaulite, (Mn,Fe)5(PO4)2 (HPO4)2 (H2O)4

Gatta¹,

Redhammer²,

Vignola³

et al. 2016

ejm

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“…Scientific interest was stimulated by the discovery that members of this series exhibit two types of magnetic behavior at low temperatures [1], particularly as it is easy to prepare as a microcrystalline powder with any composition between the manganous and ferrous end members [2,3].…”

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confidence: 99%

The Mössbauer spectrum of synthetic hureaulite: Fe5 2+(H2O)4(PO4H)2(PO4)2

et al. 2005

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The crystal structure of synthetic ferrous hureaulite, Fe 5 2+ (H 2 O) 4 (PO 4 H) 2 (PO 4 ) 2 , was refined from single-crystal X-ray data. It is monoclinic, space group C2/c, with a=17.487(4), b=9.017(2), c=9.338(2) Å , b=96.27(3)-, V=1463.6(6) Å 3 , Z=4 and D calc =3.327 g/cm 3 . This end member of the hureaulite series was crystallized under distinctly acidic conditions, by a method that gives perfect crystals, large enough for X-ray single crystal studies. The main feature of the hureaulite structure is that it has an equal number of normal (PO 4 ) 3+ and acid (PO 4 H) 2+ tetradentate groups. These are centered on Fe 2+ atoms and share corners with edge-linked octahedra, forming pentamer units. The five Fe 2+ atoms are distributed on three distinct sites in these units. This can be directly observed in the Mö ssbauer spectrum at 295 K, which contains three doublets whose relative intensities correspond to the 1:2:2 distributions of crystallographic sites.

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