Search results for "SSB"

A Mössbauer cryostat equipped with a Gifford McMahon cryocooler

1989

A new cryostat for Mossbauer spectroscopic measurements has been developed around a cryogenerator of the Gifford McMahon type operating with helium gas in a closed circuit. Both source and absorber can be cooled to about 30K and the unwanted vibrations caused by the helium compression/expansion cycle have been limited to approximately 0.05–0.06 mms−1.

Design of stable mixed-metal MIL-101(Cr/Fe) materials with enhanced catalytic activity for the Prins reaction

2020

[EN] This work highlights the benefit of designing mixed-metal (Cr/Fe) MOFs for enhanced chemical stability and catalytic activity. A robust and stable mixed-metal MIL-101(Cr/Fe) was prepared through a HF-free direct hydrothermal route with Fe(3+)content up to 21 wt%. The incorporation of Fe(3+)cations in the crystal structure was confirmed by(57)Fe Mossbauer spectrometry. The catalytic performance of the mixed metal MIL-101(Cr/Fe) was evaluated in the Prins reaction. MIL-101(Cr/Fe) exhibited a higher catalytic activity compared to MIL-101(Cr), improved chemical stability compared to MIL-101(Fe) and a higher catalytic activity for bulky substrates compared to MIL-100(Fe).In situinfra-red sp…

Interpretation of Mössbauer Parameters of Iron Compounds

1978

The task of this section is to show that for the interpretation of Mossbauer parameters — in the present case of electron densities, field gradients and magnetic hyperfine fields — bonding effects can play an important role, and free-ion or crystal field approaches may be a poor approximation.

MÖSSBAUER EFFECT STUDY ON THE HIGH-SPIN (5T2) ⇌ LOW SPIN (1A1) TRANSITION IN [Fe(2-pic)3]Cl2. DILUTION EFFECT IN [FexZn1-x(2-pic)3] Cl2. EtOH AND CRY…

1976

Valence-Delocalized and Valence-Trapped FeIIFeIII Complexes: Drastic Influence of the Ligands

1997

The two macrocyclic ligands H 2 L 1 and H 2 L 2 are not very different, but their Fe II Fe III complexes are remarkably so. [L 1 Fe 2 (μ-OAc) 2 ](ClO 4 ) is valence-delocalized on the Mossbauer time scale over the range 1.8-364 K, whereas [L 2 Fe 2 (μ-OAc)(OAc)(H 2 O)](ClO 4 )·2H 2 O is valence-trapped even at room temperature. The difference in properties of these complexes is also reflected in their electronic spectra, in their electrochemical and magnetic behavior, and in their structures.

Stoichiometry of LiNiO2 Studied by Mössbauer Spectroscopy

2002

From the 61Ni and 57Fe Mossbauer spectroscopy data follows the cationic site assignment in Li1−x Ni1+x O2. Our data explain the ferromagnetic properties of this material because of the appearance of Ni2+ (S = 1) among Ni3+ (S = 1/2) in Ni3+O2 hexagonal planes. We have no evidence for the ferromagnetic interaction between the NiO2 layers through the excess Ni2+ ions substituting the Li+ ions. The presence of Ni2+ found in the Ni3+O2 planes explains the absence of the Jahn-Teller distortions probably because of the electronic transfer between the Ni3+ and Ni2+ ions.

Alternating Chain Magnetism in Catena-μ-Oxo-Hemiporphyrazinatoiron(IV), The First μ-Oxo Linear Chain Complex Of Iron

1984

Abstract X-ray studies, Mossbauer, and magnetism show FeOHp to be an antiferromagneticaly coupled alternating chain with J = -133 cm−1, g = 2.3 and an alternation parameter of 0.4.

Magnetic Transitions in the Double Perovskite Sr2FeRe1-xFexO6(0≤X≤0.5)

2008

AbstractThe synthesis, structure, and magnetic and transport properties of solid solutions Sr2FeRe1-xFexO6 (0≤x≤0.5) are reported. A structural evolution in the solid solutions from a double perovskite to perovskite is observed with increasing Fe/Re disorder. Except for the metallic parent compound all members of the series are semiconducting. For the Fe-doped samples a change from ferrimagnetic interactions in the parent compound to a complex superposition of ferrimagnetic and antiferromagnetic interactions was observed. The magnetic moment decreases with x, whereas the Curie temperature TC remains unaffected. The magnetic and Mössbauer data suggest Fe to act as a redox-buffer.

Ni participation in the magnetism of Fe-Ni-Si-B amorphous alloys.

1987

$^{61}\mathrm{Ni}$ M\"ossbauer measurements at 4.2 K have been performed on (${\mathrm{Fe}}_{\mathrm{x}}$${\mathrm{Ni}}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$${)}_{77}$${\mathrm{Si}}_{1013}$ amorphous alloys with x=0.0, 0.1, and 0.9. Ni atoms in ${\mathrm{Ni}}_{77}$${\mathrm{Si}}_{10}$${\mathrm{B}}_{13}$ bear no magnetic moment, whereas in (${\mathrm{Fe}}_{0.1}$${\mathrm{Ni}}_{0.9}$${)}_{77}$${\mathrm{Si}}_{10}$${\mathrm{B}}_{13}$ and (${\mathrm{Fe}}_{0.9}$${\mathrm{Ni}}_{0.1}$${)}_{77}$${\mathrm{Si}}_{10}$${\mathrm{B}}_{13}$ their moments are, respectively 0.38${\ensuremath{\mu}}_{B}$ and 0.65${\ensuremath{\mu}}_{B}$. Our results, together with the literature data, show that Ni atoms in Fe-…

Spin Crossover in Fe(II) Molecular Compounds — Mössbauer and µSR Investigations

2002

The compound [Fe(ptz)6](C104)2 (ptz = 1-propyl-tetrazole) displays a complete and gradual spin crossover centred around 125 K as evidenced by magnetic and muon measurements over the temperature range ∼ 4.2–300 K. Although the crystal structure reveals only one crystallographic site, line broadening is observed in the Mossbauer spectra in the vicinity of the spin transition. The muon spin relaxation behaviour of this compound indicates that a structural transformation rather than dynamic processes may account for the observed spectral features. Both the Mossbauer and muon measurements are consistent with a mixture of high and low spin Fe ions in the transition region.