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Magnetic and structural properties of Sc(Fe1−xSix)2 Laves phases studied by Mössbauer spectroscopy and neutron diffraction

Wiertel M., Surowiec Z., Budzyński M., Sarzyński J., Beskrovnyi A. I.

Nukleonika

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2015

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Vol. 60, No. 1

155--160

EN

The investigations of iron-containing phases existing in fly ashes were performed using transmission Mössbauer spectrometry. The examined samples of fly ashes were collected from different coal combustion systems, that is, stoker-fired boiler in municipal heating plant and pulverized coal boiler in power plant. Several phases are identifi ed in the samples: iron oxides, paramagnetic aluminosilicate glass with Fe3+ ions and Al2O4- -type spinel with Fe2+ ions. It was pointed out that proportions of contents of phases strongly depend not only on the combustion temperature but also on the way of ash collection.

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Structural and magnetic properties of Sc(Fe1-xCux)2 compounds studied by means of Mössbauer effect and neutron diffraction

Wiertel M., Surowiec Z., Budzyński M., Sarzyński J.

Nukleonika

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2013

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Vol. 58, No. 1

173-178

EN

The subject of the investigations were quasibinary Sc(Fe1-xCux)2 Laves phases in which structural and magnetic properties depend on replacement of Fe atoms by Cu atoms. Powder X-ray diffraction and neutron diffraction measurements carried out at room temperature revealed that samples were a mixture of two phases: the quasibinary Sc(Fe1-xCux)2 compounds with cubic C15 structure and ScCu2 with tetragonal structure. 57Fe Mossbauer spectroscopy revealed that the Sc(Fe1-xCux)2 compounds are ferrimagnetic up to an actual concentration xact less than 0.30. A decreasing of mean values of hyperfine magnetic fields was observed. On the basis of analysis of the neutron diffraction spectra the mean values of Fe magnetic moments were determined, considering the component connected with the quasibinary Sc(Fe1-xCux)2 phases. These moments change from 1.45(29) �ĘB in the Sc(Fe0.92Cu0.08)2 to 1.18(32)mi B in Sc(Fe0.72Cu0.28)2 phase at 8 K. From the results of independent hyperfine magnetic field on 57Fe probes and magnetic Fe moments measurements, the hyperfine coupling constant in quasibinary ferrimagnetic Sc(Fe1.xCux)2 phases is estimated as equal to 13 T/mi B at room temperature.

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Structural and magnetic investigations of Sc(Fe1-xNix)2 compounds by means of Mössbauer effect and neutron diffraction

Wiertel M., Surowiec Z., Sarzyński J., Budzyński M., Beskrovnyi I.

Nukleonika

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2007

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Vol. 52, supl. 1

71-75

EN

The structural and microscopic magnetic properties of the pseudobinary Sc(Fe1 xNix)2 system were studied by XRD and Mössbauer measurements in the range of 0.10 less-than or equal to - x less-than or equal to - 0.60. All investigated samples have the cubic C15-type structure. Both the magnetic hyperfine field on 57Fe and the Curie temperature decrease with increasing Ni content and the system becomes paramagnetic for x H 0.60 at room temperature. The form and temperature dependences of the Mössbauer spectra for 0.40 less-than or equal to - x less-than or equal to - 0.50 indicate the coexistence of paramagnetic and ferromagnetic regions in the samples and occurrence of magnetic clusters with a wide distribution of the Curie temperatures. As follows from the near to zero values of quadrupole shifts in Mössbauer spectra it results that a <100> direction is a local easy magnetization axis for x e 0.10.

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Mössbauer study of magnetite nanowire in MCM-41 type mesoporous silica templates

Surowiec Z., Goworek J., Ryczkowski J., Budzyński M., Wiertel M., Sarzyński J.

Nukleonika

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2007

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Vol. 52, supl. 1

33-36

EN

Arrays of Fe3O4 nanowires embedded in mesoporous ordered silica were obtained in two ways: dissolving Fe3+ ions in an aqueous medium and their adsorption on internal and external surfaces, with the use of a Fe-EDTA complex. Magnetite polycrystalline nanowires were characterized by means of X-ray diffraction and 57Fe Mössbauer spectroscopy (MS). The average length of these nanowires is about 70 nm and their diameter is about 3 nm. Mössbauer studies evidenced that the composites consist of very small Fe3O4 particles. Almost 80% of particles exist in a paramagnetic state.

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Effect of the substitution of Ti for Y on structural properties and hyperfine interactions in Y1-xTixFe2 compounds

Surowiec Z., Sarzyński J., Budzyński M., Wiertel M.

Nukleonika

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2004

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Vol. 49,suppl.3

17-21

EN

Abstract Room temperature 57Fe Mössbauer spectroscopy and X-ray diffraction measurements are reported for a series of Y1 xTixFe2 polycrystalline samples. Our research shows that except for x = 0 and x = 1, the samples are a mixture of two C15 and C14 pseudobinary Laves phases. Some Ti atoms occupy the crystallographic positions 8a characteristic of the Y atoms in the cubic C15 structure while the rest of them form the hexagonal C14 phase. However, the lattice constant dependencies on concentration x suggest the occurrence of Y atoms in the positions 4f characteristic of Ti atoms in the hexagonal C14 structure. The partial substitution of Ti atoms for Y atoms is responsible for the HMF changes in the cubic phase. Contrary to the situation taking place in the Zr1 xTixFe2 compounds, magnetic arrangement in the pseudobinary hexagonal phases is not observed at room temperature.

6

Effect of Sc substitution for Y on structural properties and hyperfine interactions in Y1-xScxFe2 compounds

Budzyński M., Sarzyński J., Wiertel M., Surowiec Z.

Nukleonika

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2003

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Vol. 48,suppl.1

79-83

EN

Measurements of X-ray diffraction and Mössbauer effect were made on a series of Y1-xScxFe2 polycrystalline samples (x = 0.0, 0.2, 0.5, 0.7, 0.8, 1.0). It was found that the system has the cubic MgCu2 structure except for x = 1.0 where hexagonal MgZn2 structure type is stable. The lattice constant decreases with increasing x. The results of Mössbauer effect study at room temperature show that the easy axes of magnetization remain in the <111> direction for the cubic samples and <100> for the hexagonal one. Curie temperatures TC were determined from temperature dependence of the hyperfine magnetic fields. The concentration dependence of the hyperfine fields and TC show similar trends, exhibiting a maximum at x = 0.8. The magnetic and structural behaviour show that, in spite of being isoelectronic, the substitution of Y by Sc induces clear changes in the structural and magnetic properties of the compounds under investigation.