155Gd Mössbauer Spectroscopy on Intermetallics - An Overview (original) (raw)
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Mössbauer spectroscopy in modern permanent magnet alloys
Hyperfine Interactions, 1989
Intermetallic compounds involving the rare earths and a transition metal, especially iron, arousedgreat interest in the past twenty five years with particular attention been paid to their magnetic properties, due to the fact that these compounds have been used as a permanent rhagnet materials. Their study using different techniques has given new information about the mechanisms of the magnetic interactions, which are present in these compounds. Among them M'Xossbauer Spectroscopy (MS) has been proven to be an indispensable tool, due to the fact that information can be obtained either from the spectra of the iron sublattice or from the spectra of the rare earth sublattice. Thus information on local moments, crystal field effects, single ion anisotropy and exchange interactions can be extracted from such spectra and compared with results from other techniques. Among the best alloys for permanent magnet applications are the ones based on the Nd2Fe14B type structure. Very interesting magnetic properties are also present in the recently discovered series of RFe12_xM x, where M = V, Ti, Mo, Si. We will review their intrinsic and extrinsic magnetic properties, as they have been measured using (MS) and correlate them with the findings from other techniques.
We employ Mossbauer spectroscopy, high resolution resonant absorption spectroscopy of nuclei embedded in a crystal. We measure the Zeeman splitting, ratio of magnetic moments, and internal magnetic eld of 57Fe, Fe2O3, and Fe3O4. We measure the isomer shift and quadrupole splittings that occur between transitions in these spectra, as well as for FeSO4 and Fe3(SO4)2. In addition, we measure the natural linewidth of the 57Fe 14:4 keV transition. By measuring the shift in the absorption peak of our spectrum at increased temperature, we demonstrate time dilation in our results due to the second-order Doppler Shift.
Mössbauer spectroscopy in the characterisation of new materials
Hyperfine Interactions, 1994
The use of M6ssbauer spectroscopy for the characterisation of new materials is illustrated here by examples of its application in the study of different types of solids. Firstly, the incorporation of large metal ions within the channels of the compound NbTiP3012 which has a three-dimensional channel-type structure similar to that of the fast ion conductor called nasicon and the examination of the products by 57Fe and 119Sn M6ssbauer spectroscopy and X-ray powder diffraction is discussed. Secondly, the investigation by l lgsn M6ssbauer spectroscopy and X-ray photoelectron spectroscopy of new conducting tin dioxide pillared clays synthesised by microwave heating is described. Finally, the examination by 125Te MSssbauer spectroscopy and X-ray powder diffraction of conducting selenium-tellurium alloys prepared by precipitation techniques is discussed.
Magnetism and 155Gd Mössbauer spectroscopy of GdAuMg
Solid State Sciences, 2004
GdAuMg was synthesized by reaction of the elements in a sealed tantalum ampule in a high-frequency furnace. The structure was investigated by X-ray diffraction on both powders and single crystals: ZrNiAl type, P62m, a = 756.3(1), c = 412.71(7) pm, wR2 = 0.0285 for 308 F 2 values, 14 variables. Geometrical motifs of the GdAuMg structure are gold centered tricapped trigonal prisms [Au1Mg 3 Gd 6 ] and [Au2Mg 6 Gd 3 ]. Together the gold and magnesium atoms form a three-dimensional [AuMg] network in which the gadolinium atoms fill distorted hexagonal channels. Bulk magnetic properties have been investigated by means of AC and DC magnetic susceptibility measurements and 155 Gd Mössbauer spectroscopy was used to monitor the local electronic and magnetic structure. Two magnetic phase transitions were found. One transition, at T 1 = T N = 81.1(1) K, is from a paramagnetic to an antiferromagnetic state of collinear character and the other at T 2 = 19.0(1) from the antiferromagnetic to a kind of canted magnetic ordering characterized by a very narrow hysteresis loop.
Mössbauer spectroscopy as a powerful tool to study local electronic structure
2005
Mössbauer Spectroscopy, the recoil-free resonant absorption of γ-rays, is really suitable for the study of local electronic structure. Its hyperfine parameters, the isomer shift δ and quadrupole splitting ∆, respectively proportional to the s electronic density at the nucleus and to the electric field gradient, allow one to characterize the oxidation state and coordination of the probed element. Several examples illustrate the capabilities of this powerful technique for different elements (Sn, Fe, Sb) in tin oxide glasses as electrode materials for Li-ion batteries, iron phosphate glasses used for the treatment of inorganic waste and antimony chalcogenide glasses for optoelectronic applications.
Molecules, 2021
In this mini-review of our research group’s activity, the application of 57Fe Mössbauer spectroscopy in studies of electronic structure, coordination environment, and magnetic interactions in an interesting series of Fe(II/III) compounds selected is discussed. We selected two prominent phenomena that arose during investigations of selected groups of compounds carried out at different periods of time: (1) very high magnetic hyperfine fields observed at low temperatures; (2) changes in the oxidation state of the central iron atom of complexes in the solid state during interactions with gaseous O2/H2O mixtures, resulting in spin crossover (SCO).
Mossbauer spectroscopy study of the alloy system Gd(Fe1-xCox)(2)
Magnetic and Superconducting Materials, 2000
The polycrystalline inter-metallic compound Gd(Feix Co,)2 , x=0.02,0.05,0.20 has been studied by Mossbauer spectroscopy. The analysis was based on the presence of two magnetic components due to the presence of the iron in two non equivalent sites in addition to a paramagnetic component with relatively small intensity due to non identified phases The hyperfine fields By for both magnetic sites are found to increase with increasing Cobalt concentration. It is similar to the Isomer Shift IS behavior. The Bhf gradient with isomer shift is found to be 400±300 kOe/mms" 1 for the first component and 2101100 kOe/mms"' for the second one. The quadrupole shift 2e values did not vary considerably with Co concentration, this indicates that the symmetry of the atomic order around the iron sites is maintained and the Co occupied the Fe sites.