Electron Mossbauer Spectroscopy Measurements Research Articles

Microstructure, hyperfine interaction and magnetic transition of Fe-25%Ni-5%Si-x%Co alloys

Morphological and magnetic properties in Fe-25%Ni-5%Si-x%Co (x = 0, 10, 15) alloys are investigated. Scanning electron microscopy (SEM), Mossbauer spectroscopy and AC magnetic susceptibility measurements are used to determine the physical properties of alloys. The martensite morphology changed depending on the Co content. The Mossbauer study shows that the volume fraction and hyperfine field of martensite increases while isomer shift values decrease with increasing Co content. On the other hand; AC susceptibility results showed that; Co is an effective element which can be used to control both the magnetic transition and martensitic transformation temperatures.

Magnetic investigation of iron-nitride-based magnetic fluid

Transmission electron microscopy (TEM), Mossbauer spectroscopy and magnetization measurements were used in the present study to investigate a non-aqueous iron-nitride-based magnetic fluid (MF) sample containing about 2 × 1016 particle/cm3. The TEM micrographs indicated spherical-shaped iron nitride nanoparticles with an average diameter of 12.3 nm and diameter dispersity of 0.14. The 77 K Mossbauer spectrum of the frozen MF sample indicated the presence of about 95% of the γ′-Fe4N phase, with a residual 5% of the ɛ-Fe4N phase. The temperature dependence of the magnetization was investigated under zero-field-cooled (ZFC) condition, in the temperature range of 4 to 165 K. The ZFC-data were curve-fitted using a new approach that takes into account the particle size distribution and the temperature dependence of the magnetocrystalline anisotropy, making the description of the experimental situation more realistic.

Mössbauer and XRD study of pulse plated Fe–P and Fe–Ni thin layers

57Fe conversion electron Mossbauer spectroscopy, X-ray diffraction, electrochemical and magnetic measurements were used to study pulse electroplated Fe-P and Ni-Fe coatings. XRD and 57Fe CEMS measurements revealed the amorphous character of the novel pulse plated Fe-P alloys. CEM spectra indicated significant differences in the short range order and in the magnetic anisotropy between the Fe-P deposits pulse plated at medium long deposition time (t on=2 ms), with short relaxation time (t off=9 ms) and low current density (I p=0.05 Acm−2) or at short deposition time (t on=1 ms) with long relaxation time (t off=250 ms) and high current density (I p=1.0 Acm−2). The broad peaks centred around the fcc reflections in XRD of the pulse plated Ni-22 wt.% Fe deposit reflected a microcrystalline Ni-Fe alloy with a very fine, 5–8 nm, grain size. The CEM spectrum of the pulse plated Ni-22 wt.% Fe coating corresponded to a highly disordered solid solution alloy containing a minute amount of ferrihydrite. Extreme favourable soft magnetic properties were observed with these Ni-Fe and Fe-P pulse plated thin layers.

Interlayer exchange coupling, crystalline and magnetic structure in Fe/CsCl–FeSi multilayers grown by molecular beam epitaxy

Crystalline and magnetic structure as well as the interlayer exchange coupling in MBE grown Fe/FeSi multilayers are investigated. From conversion electron Mossbauer spectroscopy and ion beam channeling measurements the spacer FeSi material is found to be stabilized in a crystalline metastable metallic FeSi phase with the CsCl structure. Strong non-oscillatory interlayer exchange coupling is identified with magnetometry and synchrotron Mossbauer reflectometry. From the fits of the time spectrum and the resonant ϕ—ϕ scans a model for the sublayer magnetization of the multilayer is deduced.

Internal friction of submicrocrystalline metal

The results of a study of the structure of submicrocrystalline metals conducted with the help of transmission electron microscopy, Mossbauer spectroscopy, and calorimetric measurements are presented. The effect of the special features of the microstructure on the amplitude and temperature dependences of the internal friction in submicrocrystalline copper and steel 12Kh18N10T is estimated.

Phase Transformations Induced in Metallic Glasses by Pulsed Laser and Alpha Particle Beam Irradiation

AbstractNd:YAG laser (λ,=532 nm, τ=8 ns, Φ =30 J/cm2, v=10 Hz) induced transformations in Fe81B135Si35C2metallic glass were characterized by transmission and conversion electron Mossbauer spectroscopy, hysteresis loops and ac susceptibility measurements. The radiation-driven changes were further compared with alpha particle beam irradiation effects (W=2.8 MeV, Φ=1016and 1017 cm−2) in the same amorphous material. Pulsed laser irradiation of Fe81B135Si3.5C2 metallic glass was found to induce magnetic anisotropy, surface oxidation, onset of crystallization, slight increase in the saturation magnetic moment and changes in the imaginary susceptibility component. Alpha particle beam irradiation of Fe81B13.5Si3.5C2 metallic glass caused partial crystallization of the bulk of the specimen, total crystallization of the surface, as well as dose-dependent changes in the saturation magnetic moment, hysteresis and real susceptibility component.

Conversion electron Mössbauer study of short range ordering in electrochemically deposited Fe−Ni−Cr alloys

57Fe Conversion electron Mossbauer spectroscopy, X-ray diffractometry and electron microprobe measurements were performed on Fe−Ni−Cr alloys coatings electrochemically deposited at different times (from 1 to 29 minutes). Significant differences have been found among the Mossbauer spectra of samples examined. The changes are also reflected by the hyperfine field distribution derived from the spectra. The observed changes can be associated with changes in the magnetic anisotropy and in the short range ordering in correlated to the duration of electrochemical deposition.

Remarks on depth selective CEMS — Backscattering measurements

Depth Selective Conversion Electron Mossbauer (MB) Spectroscopy measurements usually are done in backscattering geometry under bad geometrical conditions due to low resonant count rates. Furthermore in the case of iron these investigations are often done on samples enriched with57Fe, partially polarized. Because of these conditions the spectra are modified more or less strongly by the cosine smearing effect and/or saturation effects due to high enrichment of57Fe. We have investigated these effects in the case of an α-Fe-metal sample using a high transmission orange spectrometer.