Mössbauer study of the reduction of α-Fe2O3 in hydrogen

1980 ◽  
Vol 58 (14) ◽  
pp. 1473-1475 ◽  
Author(s):  
Dimitar G. Klissurski ◽  
Ivan G. Mitov ◽  
Trifon Tomov
Keyword(s):  
Activation Energy ◽  
Hydrogen Pressure ◽  
Mössbauer Spectra ◽  
Reaction Order ◽  
Kinetics And Mechanism ◽  
Mössbauer Study ◽  
Circulation Method ◽  
Temperature Range ◽  
Mossbauer Spectra

The kinetics and mechanism of reduction of α-Fe2O3 by hydrogen has been studied by a static circulation method in the temperature range 220–350 °C. It has been established that the reaction order with respect to the hydrogen pressure is 0.86 ± 0.07 and the activation energy of the process is 17.9 ± 0.7 kcal/mol. The kinetic results and the Mössbauer spectra of specimens reduced to different degrees have shown no accumulation of wüstite phase during the reaction.

scholarly journals Mössbauer study of Fe phases in terrestrial olivine basalts from southern Egypt

Mineralogia ◽  
2013 ◽  
Vol 44 (1-2) ◽  
pp. 3-12 ◽  
Author(s):  
Kamaleldin M. Hassan ◽  
Julius Dekan
Keyword(s):  
Optical Microscopy ◽  
Crystal Chemistry ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
X Ray Diffraction ◽  
Mössbauer Study ◽  
Hyperfine Parameters ◽  
X Ray ◽  
Mossbauer Spectra ◽  
Oxidized Iron

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.

Mössbauer study of glauconites from Poland

Clay Minerals ◽  
1981 ◽  
Vol 16 (3) ◽  
pp. 221-230 ◽  
Author(s):  
A. Kotlicki ◽  
J. Szczyrba ◽  
A. Wiewióra
Keyword(s):  
Mössbauer Spectra ◽  
Mössbauer Study ◽  
Mossbauer Spectra

AbstractFour bands occur in the Mössbauer spectra of pelletal glauconites ranging in age from Cambrian to Oligocene. Components due to Fe3+ in the cis M(2) positions are visible in all the spectra but their shapes depend on the expanding layer content. In the spectrum of the Oligocene glauconite a very well-developed shoulder due to Fe2+ in the trans M(1) positions is observed. In the younger glauconites (15–20% expanding layers) the conventional assignments of the spectra indicate that Fe2+ occupies the trans M(1) positions, the cis M(2) positions being vacant. Conversely, in the Palaeozoic samples (~5% expanding layers) the cis occupancy significantly prevails over trans occupancy.

A Mössbauer study of a single crystal of the β phase of iron–germanium

1982 ◽  
Vol 60 (11) ◽  
pp. 1564-1572
Author(s):  
J. M. Daniels ◽  
H. Y. Lam ◽  
P. L. Li
Keyword(s):  
Single Crystal ◽  
Basal Plane ◽  
Mössbauer Spectra ◽  
Antiferromagnetic State ◽  
Mössbauer Study ◽  
Mossbauer Spectra ◽  
Narrow Angle ◽  
Β Phase ◽  
Line Patterns

57Fe Mössbauer spectra were obtained by scattering in a narrow angle geometry from a face, containing the basal plane, of a single crystal of the hexagonal β phase Fe1.67 Ge. Spectra were also obtained from a source of 57Co diffused into an a–c face of a single crystal of this alloy. In all cases, the spectra were satisfactorily resolved into three six-line patterns, and measurements of the relative intensities of the lines indicate that the antiferromagnetic state has a canted structure with all the spins lying in the basal plane.

scholarly journals Mössbauer study of treated Nd2Fe14B

Nukleonika ◽  
2015 ◽  
Vol 60 (1) ◽  
pp. 7-10 ◽  
Author(s):  
Mieczysław Budzyński ◽  
Virgil C. Constantin ◽  
Ana-Maria J. Popescu ◽  
Zbigniew Surowiec ◽  
Tamara M. Tkachenka ◽  
...  
Keyword(s):  
Mössbauer Spectroscopy ◽  
Grain Boundaries ◽  
Mössbauer Spectra ◽  
Mossbauer Spectroscopy ◽  
Main Phase ◽  
Surface Material ◽  
Mössbauer Study ◽  
Water Solutions ◽  
Mossbauer Spectra ◽  
Neodymium Magnets

Abstract The Nd2Fe14B cylindrical magnets were treated with water solutions of alkali, acid, and salt. Mössbauer spectroscopy was applied to study the composition and properties of the surface material of the treated magnets. It is shown that the main phase of the permanent Nd2Fe14B magnet partly decomposes. The released α-Nd at the grain boundaries interacts with water and forms neodymium hydroxide matrix, and the released Fe diffuses into it. The presence of Fe-Nd(OH)3 is reflected in the paramagnet doublet in the Mössbauer spectra of treated neodymium magnets.

scholarly journals Spin reorientation process in Tm2–xHoxFe14B – analysis of conical arrangement based on Mössbauer spectra

Nukleonika ◽  
2017 ◽  
Vol 62 (2) ◽  
pp. 123-127
Author(s):  
Piotr M. Kurzydło ◽  
Antoni T. Pędziwiatr ◽  
Bogdan F. Bogacz ◽  
Janusz Przewoźnik ◽  
Dariusz Oleszak
Keyword(s):  
Mössbauer Spectra ◽  
Magnetization Vector ◽  
Spin Reorientation ◽  
Temperature Range ◽  
Mossbauer Spectra ◽  
Fitting Procedure ◽  
Simultaneous Fitting ◽  
Spin Arrangement ◽  
Theoretical Simulations ◽  
Reorientation Process

Abstract The spin reorientation process in the Tm2-xHoxFe14B series of compounds was studied using 57Fe Mössbauer spectroscopy over the temperature range 5.2-320 K with a focus on the analysis of conical spin arrangement. Each compound was studied by precise Mössbauer scanning in the vicinity of the transition and during the transition. By applying computer simulations based on the simplified Yamada-Kato model, as well as on some literature data for R2Fe14B (R = Tm, Ho) compounds, the above series was selected for studies as it contains compounds with different spin arrangements (axial, planar, conical). It was a crucial requirement for obtaining unambiguous angular dependences when applying a simultaneous fitting procedure of Mössbauer spectra. Such an extended procedure was applied which allowed the temperature dependence of the angle describing the position of the magnetization vector to be obtained. The results were compared with those from theoretical simulations. The spin arrangement diagram was constructed. A conical spin arrangement was confirmed over a wide temperature range.

Mixed oxidation state compounds of antimony: a 121Sb Mössbauer study of some antimony–fluorine systems

1978 ◽  
Vol 56 (18) ◽  
pp. 2417-2421 ◽  
Author(s):  
Jack G. Ballard ◽  
Thomas Birchall ◽  
Ronald J. Gillespie ◽  
Edward Maharajh ◽  
David Tyrer ◽  
...  
Keyword(s):  
Oxidation State ◽  
Mössbauer Spectra ◽  
Mössbauer Study ◽  
Mossbauer Spectra ◽  
Mixed Oxidation ◽  
Mössbauer Data

Antimony-121 Mössbauer spectra for [Sb2F42+][SbF6−]2 and three compounds containing the [Sb3F14−] ion are reported. The Mössbauer data are discussed in relation to their known structures. Two of the compounds give spectra which, on analysis, give η values of unity.

THE MERCURY PHOTOSENSITIZED HYDROGENATION OF PROPYLENE AND THE ACTIVATION ENERGY OF THE REACTION C3H7+H2 = C3H8+H

1955 ◽  
Vol 33 (4) ◽  
pp. 580-588 ◽  
Author(s):  
G. R. Hoey ◽  
D. J. Le Roy
Keyword(s):  
Activation Energy ◽  
Hydrogen Pressure ◽  
Room Temperature ◽  
Linear Functions ◽  
Analogous Reaction ◽  
Temperature Range ◽  
Pressure Decrease

The reactions initiated in hydrogen–propylene mixtures by Hg(3P1) atoms were studied over the temperature range from room temperature to 320 °C. At 260° and above, the rate of formation of propane and the rate of pressure decrease are linear functions of the hydrogen pressure. This effect is attributed to the reaction C3H7+H2 = C3H8+H and its activation energy is estimated to be equal to or slightly greater than 12.5 kcal. per mole. This is 1.2 kcal. per mole greater than the corrected value for the activation energy of the analogous reaction C2H5+H2 = C2H6+H. The ratio kcombination/kdispropotionation is estimated to be approximately 2.0 at room temperature in the case of isopropyl radicals.

A125Te Mössbauer study of hexahalotellurates, pentahalotellurates, and tetrahaloaryltellurates

1981 ◽  
Vol 59 (6) ◽  
pp. 913-917 ◽  
Author(s):  
Nigel S. Dance ◽  
Pablo Dobud ◽  
Colin H. W. Jones
Keyword(s):  
Quadrupole Splitting ◽  
Mössbauer Spectra ◽  
Additive Model ◽  
Single Line ◽  
Mössbauer Study ◽  
Mossbauer Spectra ◽  
Mössbauer Parameters

The 125Te Mössbauer spectra of a number of hexahalotellurates have been measured and no significant effects of the size or symmetry of the cation on the Mössbauer parameters were observed. The mixed hexahalotellurates, M2TeX4Y2 (X, Y = Cl, Br, or I), do not exhibit a quadrupole splitting, Δ, and the trends in δ with variation in X and Y are discussed. The pentahalotellurates MTeCl5, MTeBr5, and MTeBr4Cl also yield single line spectra and this is interpreted as evidence of intermolecular bridging. The tetrahaloaryltellurates MArTeX4 and MArTeX3Y (X, Y = Cl, Br, or I) have been studied and the trends in Δ with variation X and Y are consistent with an additive model. The trends in δ are more complex.

scholarly journals Mössbauer Study of Weathered H-meteorite from the Desert of Oman

2020 ◽  
Vol 25 (1) ◽  
pp. 48
Author(s):  
Ahmed D. Al-Rawas ◽  
Abbasher M. Gismelseed ◽  
Subhi Nasir ◽  
Ali A. Yousif ◽  
Mohamed E. Elzain ◽  
...  
Keyword(s):  
Mössbauer Spectra ◽  
57Fe Mössbauer Spectroscopy ◽  
Ordinary Chondrites ◽  
Mössbauer Study ◽  
Magnetic Phases ◽  
Silicate Minerals ◽  
Mossbauer Spectra ◽  
57Fe Mossbauer Spectroscopy ◽  
H Chondrites ◽  
Terrestrial Age

A number of meteorites from the desert of Oman, classified as H-chondrites, with known and unknown ages, were studied by using 57Fe Mössbauer spectroscopy to determine their Fe3+-bearing compositions. Mössbauer spectra measured at 78 K were composed of paramagnetic doublets superimposed on magnetic sextets. The doublets are assigned to the silicate minerals olivine and pyroxene and Fe3+ phases. The magnetic sextets in most samples showed the presence of at least three magnetic phases, namely troilite, magnetite and kamacite, which commonly exist in most ordinary chondrites. The relative amounts (area %) of Fe3+ in the known-age meteorites, determined from the Mössbauer spectra, were plotted against their terrestrial ages. The plot was used to estimate the terrestrial ages of meteorites with unknown terrestrial age.

scholarly journals Kristallstruktur- und MoBbauer-Untersuchungen am Lithiumhexacyanoferrat(III)-Hexamethylentetramin-Addukt Li3[Fe(CN)6] ·2C6H12N4 · 5H20 / Crystal Structure and Mossbauer Studies of the Lithium Hexacyanoferrate(III)-Hexamethylenetetramine Adduct Li3[Fe(CN)6] · 2C6H12N4 · 5H2O

1984 ◽  
Vol 39 (9) ◽  
pp. 1162-1166 ◽  
Author(s):  
Joachim Pickardt ◽  
Jorg Kahler ◽  
Norbert Rautenberg ◽  
Erwin Riedel
Keyword(s):  
Crystal Structure ◽  
Mössbauer Spectra ◽  
Statistical Distribution ◽  
Water Molecules ◽  
Orthorhombic Space Group ◽  
Lithium Ions ◽  
Space Group ◽  
Mössbauer Studies ◽  
Temperature Range ◽  
Mossbauer Spectra

Crystals of the adduct Li3[Fe(CN)6] · 2C6H12N4-5H2O are orthorhombic, space group I2mm, Z = 2, a = 909.4(5), b = 1046.1(5), c = 1455.8(5) pm. The structure may be regarded as a packing of Fe(CN)6 octahedra and hexamethylenetetramine molecules. The lithium ions are coordinated to nitrogen atoms of both groups and to water molecules. Mossbauer spectra have been recorded for the temperature range between 290 K and 77 K. At all temperatures the spectra show two doublets with nearly identical isomer shifts but different quadrupole splittings, thus indicating the presence of two kinds of hexacyanoferrate(III) ions with slightly different distortions of the ligand spheres around the Fe atoms. The effect is discussed on the assumption of a statistical distribution of one of the lithium ions.

Sign in / Sign up

Export Citation Format

Share Document