Pyrochlores. IV. Crystallographic and Mössbauer studies of A2FeSbO7 pyrochlores

1968 ◽  
Vol 46 (24) ◽  
pp. 3829-3832 ◽  
Author(s):  
Osvald Knop ◽  
François Brisse ◽  
R. E. Meads ◽  
J. Bainbridge
Keyword(s):  
Magnetic Field ◽  
Oxygen Atom ◽  
Isomer Shift ◽  
Quadrupole Splitting ◽  
High Spin ◽  
Room Temperature ◽  
Magnetic Order ◽  
Standard Procedure ◽  
Hyperfine Magnetic Field ◽  
Mössbauer Studies

The lattice parameters and the quadrupole splittings of the room-temperature Mössbauer spectra of the cubic A2FeSbO7 pyrochlores (A = Sm, Eu, Gd, Tb, Y, Er, Lu) have been found to vary linearly with the Templeton–Dauben radii of the A3+ ions. The variation of the quadrupole splitting can be correlated with the positional parameter of the majority oxygen atom, x(O2), which determines the degree of distortion of the BO6 octahedron in cubic A2B2O7 pyrochlores. An increase of 0.1 Å in r(A3+) corresponds to a decrease of ca. 0.20 mm/s in the quadrupole splitting in the A2FeSbO7 series, and to an estimated increase of ca. 0.005 in x(O2). The isomer shift and quadrupole splitting at room temperature are typical of Fe3+(high spin) in octahedral coordination of relatively high distortion. Y2FeSbO7 at 4.2°K was found to exhibit magnetic order with a hyperfine magnetic field of approximately 400 kOe. An attempt to prepare a cubic La2FeSbO7, pyrochlore by the standard procedure was not successful.

MÖSSBAUER STUDY OF In3+ AND Al3+ ADDITIVES IN Mg–Mn FERRITES

2000 ◽  
Vol 14 (15) ◽  
pp. 1593-1601 ◽  
Author(s):  
M. SINGH ◽  
B. S. CHAUHAN
Keyword(s):  
Magnetic Field ◽  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Cation Distribution ◽  
Mössbauer Study ◽  
Mössbauer Studies ◽  
Octahedral Sites ◽  
Relaxation Effects ◽  
Experimental Errors ◽  
A Site

The effect of In 3+ and Al 3+ substitution in Mg–Mn ferrite has been studied from Mössbauer analyzes of Mg 0.9 Mn 0.1 M x Fe 2-x O 4(0 ≤x≤0.9) and Mg 0.9 Mn 0.1 Fe 2-y O 4(0≤y≤0.5) ferrites. The internal magnetic field has been found to decrease at tetrahedral and octahedral sites when the concentration of In 3+ and Al 3+ ions is successively increased. A ferromagnetic relaxation followed by paramagnetic transition is observed for higher concentrations of In 3+ ions, it has been inferred that a larger concentration of In 3+ ions enhances relaxation effects. The observed values of isomer shift corresponding to Fe 3+ ions at A as well as B sites in both the series show an insignificant variation with increase in the concentration of In 3+ and Al 3+ ions. It is also inferred that all the samples show negligible value of quadrupole splitting with in experimental errors. The occupancy ratio increases with increase of In 3+ ions and the occupancy ratio decreases with increase of concentration of Al 3+ ions. The results of occupancy of Fe 3+ ions at B to A site, as obtained from Mössbauer studies are in conformity with the cation distribution used to explain variation of 4πMs and μ0.

Mechanically Driven Dissolution of Sn in Near-Equiatomic Bcc FeCo

2012 ◽  
Vol 194 ◽  
pp. 187-193 ◽  
Author(s):  
J.M. Loureiro ◽  
Benilde F.O. Costa ◽  
Gerard Le Caër ◽  
Bernard Malaman
Keyword(s):  
Magnetic Field ◽  
Solid Solutions ◽  
Room Temperature ◽  
Hyperfine Magnetic Field ◽  
Ternary Alloys ◽  
119Sn Mössbauer Spectroscopy ◽  
X Ray Diffraction ◽  
Mechanically Alloyed ◽  
Powder Mixtures ◽  
X Ray

Ternary alloys, (Fe50−x/2Co50−x/2)Snx(x ≤ 33 at.%), are prepared by mechanical alloying from powder mixtures of the three elements. As-milled alloys are studied by X-ray diffraction and 57Fe and 119Sn Mössbauer spectroscopy. The solubility of Sn in near-equiatomic bcc FeCo is increased from ~0.5 at. % at equilibrium to ~20 at.% in the used milling conditions. The average 119Sn hyperfine magnetic field at room temperature is larger, for any x, than the corresponding fields in mechanically alloyed Fe-Sn solid solutions.

scholarly journals 57Fe and 151Eu Mössbauer studies of 3d-4f spin interplay in EuFe2−xNixAs2

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
K. Komędera ◽  
J. Gatlik ◽  
A. Błachowski ◽  
J. Żukrowski ◽  
D. Rybicki ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetic Order ◽  
Parent Compound ◽  
Density Wave ◽  
Hyperfine Magnetic Field ◽  
Spin Density Wave ◽  
Spin Reorientation ◽  
Substitution Level ◽  
Ni Substitution ◽  
The Eu

AbstractThe EuFe2−xNixAs2 (with 0 ≤ x ≤ 0.4) compounds exhibiting 3d and/or 4f magnetic order were investigated by means of 57Fe and 151Eu Mössbauer spectroscopy. Additionally, results for EuNi2As2 are reported for comparison. It was found that spin-density-wave order of the Fe itinerant moments is monotonically suppressed by Ni-substitution. However, the 3d magnetic order survives at the lowest temperature up to at least x = 0.12 and it is certainly completely suppressed for x = 0.20. The Eu localized moments order regardless of the Ni concentration, but undergo a spin reorientation with increasing x from alignment parallel to the a-axis in the parent compound, toward c-axis alignment for x > 0.07. Change of the 4f spins ordering from antiferromagnetic to ferromagnetic takes place simultaneously with a disappearance of the 3d spins order what is the evidence of a strong coupling between magnetism of Eu2+ ions and the conduction electrons of [Fe2−xNixAs2]2- layers. The Fe nuclei experience the transferred hyperfine magnetic field due to the Eu2+ ordering for Ni-substituted samples with x > 0.04, while the transferred field is undetectable in EuFe2As2 and for compound with a low Ni-substitution level. It seems that the 4f ferromagnetic component arising from a tilt of the Eu2+ moments to the crystallographic c-axis leads to the transferred magnetic field at the Fe atoms. Superconductivity is not observed down to 1.8 K, although a comparison with 57Fe and 151Eu Mössbauer data for EuFe2As2-based superconductors indicates a similar magnetic structure.

High temperature spin-polarized semiconductivity with zero magnetization in two-dimensional Janus MXenes

2016 ◽  
Vol 4 (27) ◽  
pp. 6500-6509 ◽  
Author(s):  
Junjie He ◽  
Pengbo Lyu ◽  
L. Z. Sun ◽  
Ángel Morales García ◽  
Petr Nachtigall
Keyword(s):  
High Temperature ◽  
Spin Polarization ◽  
High Spin ◽  
Room Temperature ◽  
Magnetic Order ◽  
2D Materials ◽  
Two Dimensional ◽  
Next Generation ◽  
Spin Polarized ◽  
High Spin Polarization

Searching for two-dimensional (2D) materials with room-temperature magnetic order and high spin-polarization is essential for the development of next-generation nanospintronic devices.

MÖSSBAUER EFFECT STUDIES ON LITHIUM FERRITE SUBSTITUTED WITH CHROMIUM AND ANTIMONY

2003 ◽  
Vol 17 (02) ◽  
pp. 67-73 ◽  
Author(s):  
RADHAPIYARI LAISHRAM ◽  
CHANDRA PRAKASH ◽  
SUMITRA PHANJOUBAM ◽  
H. N. K. SARMA
Keyword(s):  
Magnetic Field ◽  
Quadrupole Splitting ◽  
Cation Distribution ◽  
Room Temperature ◽  
Hyperfine Interactions ◽  
Lithium Ferrite ◽  
Mossbauer Effect ◽  
Chromium Level ◽  
Ferrite System ◽  
Nuclear Magnetic

The effect of Cr 3+ concentration on the various hyperfine interactions for the ferrite system Li 0.5+t Cr x Sb t Fe 2.5-2t-x O 4, 0.0 ≤ x ≤ 1.0, x in steps of 0.2 and t = 0.1, have been studied at room temperature using Mössbauer spectroscopy. The isomershift and the quadrupole splitting are almost negligibly influenced by the change in chromium level. The internal nuclear magnetic field, as determined from the Mössbauer spectra and the linewidth are also studied with the variation of composition. The results have been explained on the basis of various models and a cation distribution has been worked out.

Zero-Dimensional Graphene and Its Behavior under Mechanochemical Activation with Zinc Ferrite Nanoparticles

MRS Advances ◽  
2019 ◽  
Vol 5 (33-34) ◽  
pp. 1731-1737 ◽  
Author(s):  
Monica Sorescu ◽  
Matthew Knauss ◽  
Alice Perrin ◽  
Michael McHenry
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
Magnetic Properties ◽  
Isomer Shift ◽  
Ball Milling ◽  
Quadrupole Splitting ◽  
Applied Magnetic Field ◽  
Zinc Ferrite ◽  
Mechanochemical Activation ◽  
Ferrite Nanoparticles

ABSTRACTEquimolar mixtures of zero-dimensional graphene (SkySpring Nanomaterials, 1-5 nm particle size) and zinc ferrite nanoparticles (Alfa Aesar, 50 nm particle size) were exposed to mechanochemical activation by high-energy ball milling for time intervals of 0-12 hours. Their structural and magnetic properties were analyzed by Mӧssbauer spectroscopy and magnetic measurements. The spectra of zinc ferrite milled without graphene were fitted with one quadrupole-split doublet (quadrupole splitting 0.5 mm/s, isomer shift 0.23 mm/s) and indicated that zinc ferrite was superparamagnetic. The line width of the doublet increased from 0.41 to 0.64 mm/s, which correlates with a reduction in particle size as effect of the ball milling processing performed. When graphene was added to the milling powders, the Mӧssbauer spectra showed the appearance of another quadrupole doublet, with a quadrupole splitting of 0.84 mm/s and an isomer shift of -0.38 mm/s. Its abundance to the spectrum remained constant to 4.48% while the milling time was increased. This second doublet could be related to carbon atoms occupying neighborhoods in the proximity of iron atoms. Hysteresis loops were recorded in an applied magnetic field of 5 T at a temperature of 5 K. A change in the approach to saturation of the loop was observed, with saturation being achieved for the sample milled for 12 hours with graphene. Zero-field-cooling-field-cooling (ZFC-FC) was performed on all samples between 5-300 K with an applied magnetic field of 200 Oe. Graphene was found to stabilize the magnetic properties of the milled system of powders to a blocking temperature of about 90 K.

Mössbauer Study of Microbial Synthesis of Iron-Containing Nanoparticles

2015 ◽  
Vol 233-234 ◽  
pp. 766-770
Author(s):  
A.A. Shapkin ◽  
N.I. Chistyakova ◽  
D.G. Zavarzina ◽  
T.N. Zhilina ◽  
V.S. Rusakov
Keyword(s):  
Magnetic Field ◽  
Particle Size ◽  
External Magnetic Field ◽  
Wide Temperature Range ◽  
Room Temperature ◽  
Iron Reduction ◽  
Magnetic Moments ◽  
Microbial Synthesis ◽  
Mössbauer Studies ◽  
Average Size

Mössbauer studies of bioreduction products stabilized by acetone and ethanol were carried out at wide temperature range from 80 K to room temperature and in external magnetic field applied perpendicular to γ-beam at room temperature. The initial products (mixture of non-stoichiometric magnetite and maghemite) were formed during the iron reduction of synthesized ferrihydrite by bacterium G. ferrihydriticus. The addition of acetone and ethanol led to slight particle size decrease. The average size and magnetic moments were 11.2 nm and 524 µB, respectively.

Characterization of iron(II)-and iron(III)- exchanged montmorillonite and hectorite using the Mössbauer effect

Clay Minerals ◽  
1983 ◽  
Vol 18 (02) ◽  
pp. 117-125 ◽  
Author(s):  
J. A. Helsen ◽  
B. A. Goodman
Keyword(s):  
Isomer Shift ◽  
Quadrupole Splitting ◽  
Room Temperature ◽  
Ferric Iron ◽  
Free Fraction ◽  
Mossbauer Effect ◽  
Ferrous Ions ◽  
Layer Silicates ◽  
No Absorption

Abstract At room temperature both Fe(III)-exchanged montmorillonite and Fe(III)-hectorite gave similar Mössbauer spectra, each consisting of a single doublet with parameters characteristic of ferric iron. At 77 K the Fe(III)-hectorite gave a spectrum similar to that observed at room temperature, but with the montmorillonite an additional distinct doublet, with relatively large values of both isomer shift and quadrupole splitting, was observed. The Fe(II)-exchanged samples behaved very differently at room temperature and 77 K. At 77 K well-defined doublets were produced; these had quadrupole splittings similar to those shown by the ion and appreciably greater than those observed for Fe(II) in the structural sites in layer-silicates. At room temperature, however, there was no absorption corresponding to ferrous ions in either of the specimens, because the recoil-free fraction was low as a result of the loose association between the ion and the mineral lattice.

Mössbauer-Effekt-Untersuchungen an Eisen(II)-bis(α-Diimin)-Komplexen

1967 ◽  
Vol 22 (10) ◽  
pp. 1543-1550 ◽  
Author(s):  
E. König ◽  
S. Hüfner ◽  
E. Steichele ◽  
K. Madeja
Keyword(s):  
Isomer Shift ◽  
Temperature Dependence ◽  
Quadrupole Splitting ◽  
High Spin ◽  
Ground State ◽  
Axial Field ◽  
Triplet Ground State ◽  
Tentative Explanation ◽  
Back Bonding ◽  
Diimine Complexes

Fe57 MÖSSBAUER spectra have been obtained on twenty-one iron (II)-bis (α-diimine) complexes. The high-spin compounds differ from the low-spin compounds by significantly higher values of the isomer shift δ and of the quadrupole splitting ΔEQ. A recalibration of the total s-electron density is employed to determine 4s populations between 0.19 and 0.27. The order of decreasing values of δ corresponds to the nephelauxetic series, suggesting considerable back-bonding in the spin-paired configuration. The temperature dependence of ΔEQ is used to estimate values of the axial field splitting Δaxial · Six-coordinated iron (II) compounds having a triplet ground state are characterized by values of δ between 0.30 and 0.40 mm/sec, and ΔEQ between 0.18 and 0.32 mm/sec. A tentative explanation for the small ΔEQ is proposed.

scholarly journals Separation of hyperfine interactions in Mössbauer spectrocsopy

2019 ◽  
Vol 241 (1) ◽  
Author(s):  
Krzysztof R. Szymański
Keyword(s):  
Magnetic Field ◽  
Electric Field Gradient ◽  
Isomer Shift ◽  
Hyperfine Interactions ◽  
Hyperfine Magnetic Field ◽  
Hyperfine Fields ◽  
Explicit Formulas ◽  
Unpolarized Radiation ◽  
Velocity Moments

AbstractProblem of determination of isomer shift, all components of the electric field gradient and hyperfine magnetic field in case of mixed hyperfine interactions is presented. Orientation of hyperfine fields in the absorber Cartesian frame can be determined by few measurements with use of unpolarized radiation under different directions of wave vector with respect to the absorber. The method can be applied for absorbers with well separated absorption lines in their spectra. Explicit formulas for tensor components of hyperfine interactions derived from velocity moments formalism are presented.

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