Line form of Mossbauer spectra as an evidence of electron exchange in system CuO-Fe2O3

Investigations of line form and hyperfine structure parameters of Fe 57 nuclei in copper ferrites were carried out by Mossbauer spectroscopy. It is shown that increasing of synthesis temperature leads to redistribution of copper and iron ions among lattice sites. This results in changing of local magnetic fields at iron nuclei and varying of relative intensities of spectrum components. However, detailed study of Mossbauer spectrum line forms for all samples did not allow to detect the influence of nearest cations environment of iron ions in octohedral sites on local field value, which is the case in other spinel structure ferrites. One of possible reasons is strong electron exchange between Cu and Fe ions in octahedral sublattice

Magnetic nanostructured polymer composites

Magnetic polymer composites filled with microparticles of the nanocrystalline 5BDSR alloy have been studied. Measurements have been performed mainly by the ferromagnetic resonance method complemented by other spectroscopic methods. A quasi-stepwise structure of spectra near the direction of the magnetic field perpendicular to the nanocomposite plate has been found. It has been shown that incorporation of nanoparticles of technical carbon into the composite leads to a nonmonotonic concentrational dependence of the broadening of spectral lines, which is caused by spatial variations in the perpendicular magnetic anisotropy. The ferromagnetic resonance spectrum has been processed by taking into account the scatter of the magnetic anisotropy and demagnetizing factors. © 2011 Pleiades Publishing, Ltd

Study of the magnetic phase separation in the Eu0.65Sr0.35Mn1-xFexO3 ceramics by EPR and Mössbauer spectroscopy

The structural and magnetic properties of the Eu0.65Sr0.35Mn1-xFexO3 (x = 0.2-0.4) ceramics have been investigated using EPR, Mössbauer spectroscopy, and differential thermomagnetic analysis. A magnetic phase separation has been revealed in the structurally single-phase samples. © 2010 Pleiades Publishing, Ltd

Mössbauer investigations of magnetic system stratification in europium and thulium ferromanganites

Strontium-substituted ferromanganites of europium and thulium were investigated. Samples of Eu0.65Sr0.35Mn 1-xFexO3 and Tm0.65Sr 0.35Mn1-xFexO3 were prepared using ceramic processing. Based on the data from X-ray analysis, the samples with europium had a perovskite lattice, whereas the thulium samples were crystallized in an ilmenite lattice. Stratification of the magnetic subsystem was observed in the Mössbauer spectra of certain samples at T ≈ 300 K. © Allerton Press, Inc., 2010

Controlling Magnetization Reversal and Hyperthermia Efficiency in Core-Shell Iron-Iron Oxide Magnetic Nanoparticles by Tuning the Interphase Coupling

Magnetic particle hyperthermia, in which colloidal nanostructures are exposed to an alternating magnetic field, is a promising approach to cancer therapy. Unfortunately, the clinical efficacy of hyperthermia has not yet been optimized. Consequently, routes to improve magnetic particle hyperthermia, such as designing hybrid structures comprised of different phase materials, are actively pursued. Here, we demonstrate enhanced hyperthermia efficiency in relatively large spherical Fe/Fe-oxide core-shell nanoparticles through the manipulation of interactions between the core and shell phases. Experimental results on representative samples with diameters in the range 30-80 nm indicate a direct correlation of hysteresis losses to the observed heating with a maximum efficiency of around 0.9 kW/g. The absolute particle size, the core-shell ratio, and the interposition of a thin wüstite interlayer are shown to have powerful effects on the specific absorption rate. By comparing our measurements to micromagnetic calculations, we have unveiled the occurrence of topologically nontrivial magnetization reversal modes under which interparticle interactions become negligible, aggregates formation is minimized and the energy that is converted into heat is increased. This information has been overlooked until date and is in stark contrast to the existing knowledge on homogeneous particles

Line form of Mossbauer spectra as an evidence of electron exchange in system CuO-Fe2O3

Investigations of line form and hyperfine structure parameters of Fe 57 nuclei in copper ferrites were carried out by Mossbauer spectroscopy. It is shown that increasing of synthesis temperature leads to redistribution of copper and iron ions among lattice sites. This results in changing of local magnetic fields at iron nuclei and varying of relative intensities of spectrum components. However, detailed study of Mossbauer spectrum line forms for all samples did not allow to detect the influence of nearest cations environment of iron ions in octohedral sites on local field value, which is the case in other spinel structure ferrites. One of possible reasons is strong electron exchange between Cu and Fe ions in octahedral sublattice

Line form of Mossbauer spectra as an evidence of electron exchange in system CuO-Fe2O3

Investigations of line form and hyperfine structure parameters of Fe 57 nuclei in copper ferrites were carried out by Mossbauer spectroscopy. It is shown that increasing of synthesis temperature leads to redistribution of copper and iron ions among lattice sites. This results in changing of local magnetic fields at iron nuclei and varying of relative intensities of spectrum components. However, detailed study of Mossbauer spectrum line forms for all samples did not allow to detect the influence of nearest cations environment of iron ions in octohedral sites on local field value, which is the case in other spinel structure ferrites. One of possible reasons is strong electron exchange between Cu and Fe ions in octahedral sublattice