Petrogenetic implication of the Mössbauer hyperfine parameters of Fe3+-chromites from Sukinda (India) ultramafites

1991 ◽  
Vol 55 (381) ◽  
pp. 535-542 ◽  
Author(s):  
Sachinath Mitra ◽  
Tapan Pal ◽  
Taraknath Pal
Keyword(s):  
Mössbauer Spectroscopy ◽  
Spinel Structure ◽  
Mossbauer Spectroscopy ◽  
Nearest Neighbour ◽  
Complete Conversion ◽  
Hyperfine Parameters ◽  
Octahedral Sites ◽  
Magmatic Stage ◽  
Rate Of Cooling ◽  
Ore Zones

AbstractChromites from two horizons of the Sukinda area (India) marked as ‘grey ore’ and ‘brown ore’ zones have been studied by 57Fe Mössbauer spectroscopy, which revealed that both chromite types are oxidised and have a type of disordered spinel structure in which octahedral sites are occupied by Fe2+ ions.The spectra of the grey ore sample can be fitted to three doublets corresponding to Fe2+ (A), Fe3+ (A) and Fe2+ (B) sites. This sample is less oxidised than the brown ore, in which progressive oxidation in the magmatic (?) stage led to the complete conversion of Fe2+ in A sites to Fe3+. The spectra of the brown ore are characterised by two doublets correpsonding to two tetrahedral (A) sites of Fe3+ with different next-nearest neighbour configurations and a third doublet for Fe2+ at the B site. The brown ores have higher chromium and Fe3+ content and have lesser amounts of Ni and Al in comparison to the grey ores. Megascopically, the former shows larger crystal sizes. The high Fe3+ content in the brown ore suggests that this type of chromite was formed in a region of high ƒO2 in the magmatic environment. This perhaps occurred at the part of the mantle where the temperature was higher and the rate of cooling was slower than that of the grey ores which crystallised in the magmatic melt.

scholarly journals Biomedical application of Mössbauer spectroscopy with a high velocity resolution: Revealing of small variations

2010 ◽  
Vol 24 (6) ◽  
pp. 593-599 ◽  
Author(s):  
M. I. Oshtrakh ◽  
V. A. Semionkin ◽  
O. B. Milder ◽  
I. V. Alenkina ◽  
E. G. Novikov
Keyword(s):  
Mössbauer Spectroscopy ◽  
Biomedical Research ◽  
High Velocity ◽  
Mossbauer Spectroscopy ◽  
Biomedical Application ◽  
Hyperfine Parameters ◽  
High Velocity Resolution ◽  
Mößbauer Spectroscopy ◽  
Chicken Spleen ◽  
Chicken Liver And Spleen

Application of Mössbauer spectroscopy with a high velocity resolution for study different hemoglobins, ferritin, its models and chicken liver and spleen as well as normal and lymphoid chicken spleen demonstrated revealing of small variations of hyperfine parameters related to small variations of iron stereochemistry in biomolecules. These data demonstrate that Mössbauer spectroscopy with a high velocity resolution may be useful in biomedical research to distinguish small variations of iron-containing proteins in normal and pathological cases.

Magnetically modified bentonite as a possible contrast agent in MRI of gastrointestinal tract

2007 ◽  
Vol 61 (5) ◽  
Author(s):  
H. Bartonkova ◽  
M. Mashlan ◽  
I. Medrik ◽  
D. Jancik ◽  
R. Zboril
Keyword(s):  
Mössbauer Spectroscopy ◽  
Iron Oxide ◽  
Contrast Agent ◽  
Mossbauer Spectroscopy ◽  
Oxide Particle ◽  
Negative Contrast ◽  
Iron Oxide Particle ◽  
Hyperfine Parameters ◽  
Mößbauer Spectroscopy ◽  
Negative Contrast Agent

AbstractA composite of iron oxide nanoparticles and mineral matrix has been studied by XRD, Mössbauer spectroscopy, and TEM. Magnetite and superparamagnetic magnetite have been identified by Mössbauer spectroscopy in the nanocomposite. A relationship between the hyperfine parameters and iron oxide particle size has been confirmed by TEM. The optimal concentration of “magnetite—bentonite” composite, when the MRI signal is fully reduced, was found for using this composite as a negative contrast agent.

Iron phases identified in bentonite from the Lieskovec deposit (Slovakia) by variable-temperature Mössbauer spectroscopy

Clay Minerals ◽  
2008 ◽  
Vol 43 (1) ◽  
pp. 107-115 ◽  
Author(s):  
P. Komadel ◽  
A. S. Anastácio ◽  
S. Andrejkovičová ◽  
J. W. Stucki
Keyword(s):  
Mössbauer Spectroscopy ◽  
Mossbauer Spectroscopy ◽  
Variable Temperature ◽  
Fine Fraction ◽  
Morin Transition ◽  
Hyperfine Parameters ◽  
Mößbauer Spectroscopy ◽  
Fe Content ◽  
Wet Chemical ◽  
Low Charge

AbstractThe clay-mineral fraction of samples from a bentonite deposit in the Zvolenská kotlina Basin (Slovakia), formed by the alteration of andesitic pyroclastics, was dominated by Fe-bearing montmorillonite of relatively low charge. The total Fe content of the samples ranged from 3.58 to 5.81 wt.% Fe. Variable-temperature Mössbauer spectroscopy revealed that structural Fe(III) in smectite accounts for 70–90% of the total Fe in the unfractionated samples. No structural Fe(II) was observed by Mössbauer spectroscopy, but a small amount was detected by wet chemical analysis. The remainder of the Fe is present in oxide and/or oxyhydroxide phases dominated by poorly ordered goethite and hematite. The hyperfine parameters of the Mössbauer spectra for the raw bentonite are consistent with structural Fe(III) in an aluminosilicate phase mixed with varying quantities of hematite, goethite and possibly maghemite. Except in the fine fraction of sample L28, the hematite failed to undergo the Morin transition, as shown by the negative values for quadrupole splitting at 298 K and 6 K.

Decomposition of CO2 to carbon by H2-reduced Ni(II)- and Co(II)-bearing ferrites at 300 °C

1994 ◽  
Vol 9 (2) ◽  
pp. 462-467 ◽  
Author(s):  
T. Kodama ◽  
H. Kato ◽  
S.G. Chang ◽  
N. Hasegawa ◽  
M. Tsuji ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Mössbauer Spectroscopy ◽  
Spinel Structure ◽  
Mossbauer Spectroscopy ◽  
High Reactivity ◽  
Metal Substitution ◽  
Spinel Type ◽  
Mößbauer Spectroscopy ◽  
Xrd Studies ◽  
Different Levels

Ni(II)- and Co(II)-bearing ferrites with different levels of metal substitution have been studied for CO2 decomposition. Ni2+ and Co2+ have been substituted for Fe2+ or Fe3+ in magnetite with the spinel type of crystal structure up to 14% and 26% for the mole ratio of Ni2+ and Co2+ to the total Fe contents, respectively. The metal substitution was corroborated by Mössbauer spectroscopy and XRD studies. They were activated in a flow of H2 gas to form oxygen-deficient ferrites with the spinel structure retained. The oxygen-deficient M(II)-bearing ferrites have been found to show high reactivity toward CO2 decomposition to carbon at 300 °C. The reactivity increased with the level of metal substitution and activation. The oxygens of CO2 were incorporated into the spinel structure and carbon was deposited on the surface of the ferrites. The deposited carbon was visible on dissolution of the ferrites used. The rate of decomposition on H2-activated Ni(II)-bearing ferrite with the mole ratio of 14% was 30 times as high as that of H2-activated magnetite.

Structural studies of montmorillonites by 57Fe Mössbauer spectroscopy

Clay Minerals ◽  
1987 ◽  
Vol 22 (4) ◽  
pp. 387-394 ◽  
Author(s):  
C. M. Cardile
Keyword(s):  
Mössbauer Spectroscopy ◽  
Mossbauer Spectroscopy ◽  
57Fe Mössbauer Spectroscopy ◽  
Structural Studies ◽  
Site Occupation ◽  
57Fe Mössbauer ◽  
Octahedral Sites ◽  
57Fe Mossbauer Spectroscopy ◽  
Mößbauer Spectroscopy

AbstractFive montmorillonites were analysed by 57Fe Mössbauer spectroscopy and their Fe3+ occupation in tetrahedral and octahedral sites assigned. The montmorillonites, with a range of IVFe3+ contents, were used in an attempt to correlate IVFe3+ content with VIFe3+cis- and trans-OH site occupation to verify the assertion that increasing IVFe3+ content directs VIFe3+ to cis-OH sites. However, VIFe3+ in montmorillonite appears to be located essentially in the trans-OH sites. The two doublets computer-fitted to the VIFe3+ Mössbauer resonance for montmorillonite appear to represent a distribution of a continuum of slightly different Fe3+ resonances, which arise from the variable atomic environment surrounding the VIFe3+ sites, rather than discrete cis- and trans-OH sites. Therefore Mössbauer spectroscopy cannot be used to demonstrate whether an increasing IVFe3+ content directs VIFe3+ substitution into particular sites for montmorillonites.

Sign in / Sign up

Export Citation Format

Share Document