X-ray diffraction and57Fe Mössbauer spectra of the system Fe2O3−Ga2O3

1989 ◽  
Vol 24 (8) ◽  
pp. 2722-2726 ◽  
Author(s):  
S. Musić ◽  
S. Popović ◽  
M. Ristić
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

1992 ◽  
Vol 128 (1) ◽  
pp. 249-254 ◽  
Author(s):  
Nestor E. Massa ◽  
Stella Duhalde ◽  
Carlos Fainstein ◽  
Celia Saragovi ◽  
Pablo Etchegoin

Clay Minerals ◽  
1979 ◽  
Vol 14 (4) ◽  
pp. 273-283 ◽  
Author(s):  
E. Murad

Abstractβ-FeOOH (akaganéite) was prepared by slow hydrolysis of an FeCl3 solution. X-ray diffraction measurements gave refined unit-cell parameters of a=10·535 Å, c=3·030 Å.Two doublets with δ(Fe)=0·39, ΔEQ=0·95, and δ=0·38, ΔEQ=0·55 mm s−1, respectively, can be fitted to the Mössbauer spectrum taken at room temperature.Magnetically split Mössbauer spectra were registered at 135 and 4°K. These can be resolved into at least three superimposed sextets, corresponding to different Fe3+ sites in the β-FeOOH structure. At 4°K a three sextet model gives parameters of δ=0·36, ΔEQ=0·90, Hi=473; δ=0·35, ΔEQ=0·30, Hi=479; and δ=0·37, ΔEQ=−0·05 mm s−1, Hi=486kOe, respectively.The complexity of the Mössbauer spectra of β-FeOOH limits the usefulness of this method as a tool for the identification of akaganéite in composite natural samples.


2008 ◽  
Vol 2008 ◽  
pp. 1-7 ◽  
Author(s):  
R. L. Dhiman ◽  
S. P. Taneja ◽  
V. R. Reddy

Aluminum doped manganese ferritesMnAlxFe2−xO4with0.0≤x≤1.0have been prepared by the double ceramic route. The formation of mixed spinel phase has been confirmed by X-ray diffraction analysis. The unit cell parameter `aO' is found to decrease linearly with aluminum concentration due to smaller ionic radius of aluminum. The cation distributions were estimated from X-ray diffraction intensities of various planes. The theoretical lattice parameter, X-ray density, oxygen positional parameter, ionic radii, jump length, and bonds and edges lengths of the tetrahedral (A) and octahedral (B) sites were determined.57Fe Mössbauer spectra recorded at room temperature were fitted with two sextets corresponding to Fe3+ions at A- and B-sites. In the present ferrite system, the area ratio of Fe3+ions at the A- and B-sites determined from the spectral analysis of Mössbauer spectra gives evidence that Al3+ions replace iron ions at B-sites. This change in the site preference reflects an abrupt change in magnetic hyperfine fields at A- and B-sites as aluminum concentration increases, which has been explained on the basis of supertransferred hyperfine field. On the basis of estimated cation distribution, it is concluded that aluminum doped manganese ferrites exhibit a 55% normal spinel structure.


1990 ◽  
Vol 43 (9) ◽  
pp. 1559 ◽  
Author(s):  
AM Vandenbergen ◽  
JD Cashion ◽  
GD Fallon ◽  
BO West

Single-crystal X-ray diffraction studies have been carried out on the tetradentate SnII complex N,N′-(4,5-dimethyl-1,2-phenylene ) bis ( salicylideneiminato )tin(II) [ Sn ( saldph )] and the tetradentate complex N-(2-oxidophenyl) salicylideneiminatotin (II) [ Sn ( salop )]. Sn ( saldph ) is a monomer and has the SnII ion 1.126(1)Ǻ above the plane of the O2N2 donors while Sn ( salop ) is dimeric with bridging between SnII ions by the oxygens of the oxidophenyl groups. SnII ions are raised above the O3N donor planes by 1.109(7)Ǻ while the molecules are bent along the bridging O-O axis with a dihedral angle between the chelate planes of 92.1°. The Mossbauer spectra of the complexes are reported. The SnII salicylideneimines react with H2O and oxygen but are inert to alkyl halides.


Fuel ◽  
1979 ◽  
Vol 58 (9) ◽  
pp. 687-688 ◽  
Author(s):  
R.H. Shiley ◽  
S.J. Russell ◽  
D.R. Dickerson ◽  
C.C. Hinkley ◽  
G.V. Smith ◽  
...  

1990 ◽  
Vol 9 (8) ◽  
pp. 872-875 ◽  
Author(s):  
M. Ristic ◽  
S. Popović ◽  
S. Musić

2012 ◽  
Vol 11 (05) ◽  
pp. 1250036 ◽  
Author(s):  
WEIGAO WANG ◽  
FAGEN LI ◽  
FAN ZHAO ◽  
JUN WANG ◽  
GUOMENG ZHAO

Fe7S8 nanorods have been successfully synthesized using a chemical evaporation method. X-ray diffraction pattern showed that the as-prepared products were Fe7S8 with no impurity phase. The results of scanning electron microscopy indicated that the samples synthesized at 750°C and 900°C were rod and sheet-like, respectively. The magnetic properties of the iron sulfide nanorods were measured over a wide temperature range (4 K–750 K) using a quantum design vibrating sample magnetometer. It was found that the nanorods were ferromagnetic with the Curie temperature of about 581 K. The Mössbauer spectra showed that the iron sulfide nanorods consisted of hexagonal pyrrhotites, whose spectra were asymmetrical according to correlation between the isomer shift and the hyperfine field.


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