scholarly journals Verteilung und Valenz der Kationen in Spinellsystemen mit Eisen und Vanadium, III Röntgenographische und Mößbauer-spektroskopische Untersuchung des Spinellsystems ZnFeVO4-Fe3O4 / Distribution and Valence of the Cations in Spinel Systems with Iron and Vanadium, III X-ray Investigation and Mössbauer Spectra of the Spinel System ZnFeVO4-Fe3O4

1981 ◽  
Vol 36 (10) ◽  
pp. 1228-1233 ◽  
Author(s):  
Erwin Riedel ◽  
Hümeyra Anik ◽  
Till Dützmann

Abstract The spinel system Zni_zFe2:[Fei+2;Vi_I]04 has been prepared by heating mixtures of ZnFeV(>4 and Fe3Ü4 at 1000 °C. The lattice constants, the oxygen parameters and the Mössbauer parameters show that a transition from a nearly normal to an inverse distribu-tion of Fe(II) and Fe(III) exists.

1980 ◽  
Vol 35 (10) ◽  
pp. 1257-1260 ◽  
Author(s):  
Erwin Riedel ◽  
Till Dützmann ◽  
Norbert Pfeil

Abstract The spinel system Zn[FexV2-x]O4 has been prepared by heating mixtures of ZnV2O4 and ZnFe2O4 at 1000 °C. The lattice constants increase linearly with x by 3.6 pm, the oxygen parameters are constant with a mean value u = 0.384s. The parameters of room temperature Mössbauer spectra show that in the whole series V(III) and Fe(III) are present.


1983 ◽  
Vol 38 (12) ◽  
pp. 1630-1634 ◽  
Author(s):  
Erwin Riedel ◽  
Hümeyra Anik

In the spinel system FeV2O4-ZnV2O4 pure Fe(II)-spinels could not be prepared. Mössbauer spectra show that the solid solution has the composition Fex2+ Zn1-x:[Fey3+ V2-y]O4, y depending on the partial pressure of oxygen during preparation. The reaction of 1/3 Fe + 1/3 Fe2O3 + V2O3 in a closed tube was also studied by X-ray and Mössbauer investigation


1982 ◽  
Vol 37 (5) ◽  
pp. 610-613 ◽  
Author(s):  
Hartwig Schäfer-Stahl ◽  
Josef Schneider ◽  
Gottfried Huttner

Room-temperature Mössbauer spectra are reported for μ3-RP-bridged heterometallic iron clusters of the type μ3-RP-(C5H5(CO)2Mn)Fe2(CO)6Ln. The Mössbauer parameters of these clusters show that the structures are in agreement with the lattice constants of low-spin hetero manganese-iron clusters


2010 ◽  
Vol 65 (1) ◽  
pp. 90-94 ◽  
Author(s):  
Thomas Harmening ◽  
Rainer Pöttgen

Samples of EuRu4B4 and of the new boride EuRuB4 were prepared from europium, RuB, and RuB4 precursor alloys, respectively, in sealed tantalum tubes in an induction furnace. EuRu4B4 crystallizes with the LuRu4B4 structure, a = 748.1(1), c = 1502.3(4) pm. The structure of EuRuB4 was refined on the basis of X-ray diffractometer data: Pbam, a = 599.7(1), b = 1160.7(3), c = 358.06(7) pm, wR2 = 0.0691, 474 F2 values, and 38 variables. The four crystallographically independent boron sites build up layers which consist of almost regular pentagons and heptagons which sandwich the ruthenium and europium atoms, respectively. Within the two-dimensional [B4] networks each boron atom has a slightly distorted trigonal-planar boron coordination with B-B distances in the range 172 - 186 pm. Temperature-dependent 151Eu Mössbauer spectra show stable trivalent europium for EuRu4B4 and EuRuB4


Author(s):  
Amel Kaibi ◽  
Abderrahim Guittoum ◽  
Nassim Souami ◽  
Mohamed Kechouane

Nanocrystalline Ni75Fe25 (Ni3Fe) powders were prepared by mechanical alloying process using a vario-planetary high-energy ball mill. The intermetallic Ni3Fe formation and different physical properties were investigated, as a function of milling time, t, (in the range 6 to 96 h range), using X-Ray Diffraction (XRD) and Mössbauer Spectroscopy techniques. X-ray diffraction were performed on the samples to understand the structural characteristics and get information about elements and phases present in the powder after different time of milling. The refinement of XRD spectra revealed the complete formation of fcc Ni (Fe) disordered solid solution after 24 h of milling time, the Fe and Ni elemental distributions are closely correlated. With increasing the milling time, the lattice parameter increases and the grains size decreases. The Mössbauer experiments were performed on the powders in order to follow the formation of Ni3Fe compound as a function of milling time. From the adjustment of Mössbauer spectra, we extracted the hyperfine parameters. The evolution of hyperfine magnetic field shows that the magnetic disordered Ni3Fe phase starts to form from 6 h of milling time and grow in intensity with milling time. For the milling time more than 24 h, only the Ni3Fe disordered phase is present with a mean hyperfine magnetic field of about 29.5 T. The interpretation of the Mossbauer spectra confirmed the results obtained by XRD.


Mineralogia ◽  
2013 ◽  
Vol 44 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
Kamaleldin M. Hassan ◽  
Julius Dekan

AbstractOlivine basalts from southern Egypt were studied by 57Fe Mössbauer spectroscopy at 297 and 77 K, and by optical microscopy and X-ray diffraction. The 57Fe Mössbauer spectra show three-magnetic sextets, three doublets of ferrous (Fe2+), and a weak ferric (Fe3+) doublet that is attributable to a nanophase oxide (npOx). The magnetic sextets relate to titanomagnetite and the Fe2+ doublets to olivine, pyroxene, and ulvöspinel. Variations in the hyperfine parameters of the various Fe components are attributed to changes in the local crystal chemistry. The intensity of oxidation (Fe3+/ΣFe) in the rocks varies from 20-27% with the oxidized iron largely residing in the titanomagnetite.


1991 ◽  
Vol 10 (4) ◽  
pp. 197-200 ◽  
Author(s):  
S. Musić ◽  
S. Popović ◽  
M. Metikoš-Hukovć ◽  
V. Gvozdić

2008 ◽  
pp. 462-466
Author(s):  
Harald Stger ◽  
Hermann Rautz ◽  
Guido Kickelbick ◽  
Claus Pietzsch

Clay Minerals ◽  
1988 ◽  
Vol 23 (4) ◽  
pp. 367-377 ◽  
Author(s):  
D. H. Doff ◽  
N. H. J. Gangas ◽  
J. E. M. Allan ◽  
J. M. D. Coey

AbstractPillared smectites in which the pillars consist of iron oxide are expected to have interesting and unusual magnetic properties. Several possible routes by which such materials might be made have been investigated, namely intercalation of hydroxy-Fe(III) polycations, mixed hydroxy-Fe(III)/Al polycations, phenanthroline-Fe(II) cations, and trinuclear Fe(III) acetato cations into Na-montmorillonite. Only the last of these yielded a pillared clay (PILC) on calcination. The products have been characterized using X-ray powder diffraction and 57Fe Mössbauer spectroscopy. The precursor Fe-PILC has a d-spacing of 21 Å and expands to 23 Å on solvation with glycol. The calcined Fe-PILC has a d-spacing of 19 Å (gallery height 9·4 Å) and does not expand with glycol, confirming cross-linking of the layers. From Mössbauer spectra at 4·2 K it is estimated that there are of the order of some hundred Fe atoms per pillar.


2005 ◽  
Vol 61 (3) ◽  
pp. 250-257 ◽  
Author(s):  
Serena C. Tarantino ◽  
Paolo Ghigna ◽  
Catherine McCammon ◽  
Roberta Amantea ◽  
Michael A. Carpenter

The MnNb2O6–FeNb2O6 solid solution has been investigated by Fe–K- and Mn–K-edge X-ray absorption (XANES and EXAFS), and Mössbauer spectroscopy. The first-shell M—O bond lengths deduced from EXAFS show a fairly small compositional dependence. A degree of static disorder, which increases with increasing manganese content, is clearly seen by the loss of correlation for the next-neighbour (NN) interaction. Hyperfine parameters from Mössbauer spectra are consistent with variations in the average environment, as recorded by X-ray data. Line broadening of the Mössbauer spectra provides evidence for next-neighbour effects and is consistent with there being no significant clustering of Fe or Mn within the samples. There appear to be differences in the way the columbite structure accommodates Fe2+ and Mn2+ ions. In ferrocolumbite all the Fe octahedra are close to being identical, while there are local structural heterogeneities at a longer length scale, presumably in ordering the precise topology of polyhedra immediately adjacent to the octahedron. By contrast, the manganocolumbite seems to have some diversity in the precise coordination at the MnO6 octahedra, but a greater uniformity in how the adjacent polyhedra are configured around them.


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