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Strona główna » Instytut » Pracownicy » Marek Wiertel

dr Marek Wiertel

Zakład

Zakład Metod Jądrowych

Stanowisko:

specjalista nauk.-tech.

Kontakt:

pokój: 36
telefon: (081) 537-62-20
e-mail: marek.wiertel@umcs.pl

Specjalność naukowa:

fizyka

Publikacje: Ukryj abstrakty

  1. Z. Surowiec,M. Wiertel,R. Zaleski,M. Budzyński, Positron annihilation study of iron oxide nanoparticles in mesoporous silicate MCM-41 template, Nukleonika, 55(), 2010, 91-96

  2. Surowiec, Z. Sarzynski, J. Budzynski, M. Wiertel, M., Effect of the substitution of Ti for Y on structural properties and hyperfine interactions in Y1-xTixFe2 compounds, Nukleonika, 49(), 2004, S17-S21

    Abstract:
    Room temperature Fe-57 Mossbauer 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.

  3. Budzynski, M. Sarzynski, J. Wiertel, M. Surowiec, Z., Effect of Sc substitution for Y on structural properties and hyperfine interactions in Y1-xScxFe2 compounds, Nukleonika, 48(), 2003, S79-S83

    Abstract:
    Measurements of X-ray diffraction and Mossbauer 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 Mossbauer 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 T-C were determined from temperature dependence of the hyperfine magnetic fields. The concentration dependence of the hyperfine fields and T-C 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.

  4. Surowiec, Z. Wiertel, M. Beskrovnyi, A. I. Sarzynski, J. Milczarek, J. J., Investigations of microscopic magnetic properties of the pseudo-binary system (Zr1-xTix)Fe-2, Journal of Physics-Condensed Matter, 15(37), 2003, 6403-6414

    Abstract:
    The magnetic structure and hyperfine interactions in the polycrystalline pseudobinary system (Zr1-xTix)Fe-2 for x less than or equal to 0.2 and x greater than or equal to 0.7 were studied using the techniques of neutron diffraction and the Mossbauer effect. The results of our measurements reveal the cubic C 15 and the hexagonal C 14 crystal structure for low and high Ti atom concentration x, respectively. For the ferrimagnetic region of the C15 structure the reduction from 1.58(5) to 1.30(6) muB of Fe magnetic moments with increasing x at room temperature was found. The presence of two hyperfine magnetic fields in the antiferromagnetic C14 phases suggests the existence of small magnetic moments on Fe atoms at 2a in addition to those present at the 6h sites. The magnetic structure refinement for the (Zr0.3Ti0.7)Fe-2 alloy yielded magnetic moments perpendicular to the c axis of 0.19(10) mu(B) at Fe 2a sites at 10 K. The results confirm the spin-canted antiferromagnetic structure with a canting angle of 8degrees at 10 K in the pseudo-binary phase.

  5. Budzynski, M. Sarzynski, J. Surowiec, Z. Wiertel, M., Mossbauer and X-ray diffraction studies of Zr1-xTixFe2 Laves phase compounds, Acta Physica Polonica A, 100(5), 2001, 717-722

    Abstract:
    Mossbauer spectroscopy of Fe-57 and X-ray diffraction measurements in the Zr1-xTixFe2 phase have been made. Our X-ray diffraction spectra revealed that the samples have the cubic C15 crystal structure for low Ti concentration and the hexagonal C14 structure for high Ti concentration. In the range of 0.2 less than or equal to x less than or equal to 0.5 a mixture of both structures occurs. The investigated compounds are paramagnetic at RT for x > 0.80 and magnetic for x less than or equal to 0.8. In the magnetic samples we found four different values of hyperfine magnetic fields. The presence of two hyperfine magnetic fields in the C14 phase suggests magnetic moments on Fe atoms at 2a sites. The obtained epsilon (Q) vs. the x dependence indicates the spin canted antiferromagnetic structure in the hexagonal phase in the range of 0.2 less than or equal to x less than or equal to 0.8.

  6. Tarkowski, P. Sarzynski, J. Budzynski, P. Paluch, R. Wiertel, M., Influence of the kind of fuel oil on the deposit composition in the diesel engine combustion chamber, Fuel, 80(10), 2001, 1399-1403

    Abstract:
    The authors studied deposits from combustion chambers of high- pressure engines supplied with standard fuel (SO) and ecological fuel of City-Diesel type. Chemical analysis, X-ray diffractograms, Mossbauer absorption and additionally Raman wavenumber measurements were made. The wearing of some engine elements was examined by the profilometric method. By using ecological fuel, the deposits were shown to contain four to five times less iron compounds than standard fuel supply. This accounts for a smaller attrition of the combustion chamber elements, and thus longer durability of the engine. (C) 2001 Elsevier Science Ltd. All rights reserved.

  7. Sarzynski, J. Wiertel, M. Budzynski, M., Influence of the local environment on the hyperfine interactions in Zr(Fe1-xCox)(2) compounds, Hyperfine Interactions, 108(4), 1997, 381-387

    Abstract:
    Ferromagnetic Laves phase compounds Zr(Fe1-xCox)(2) have been investigated by means of the Mossbauer effect (Fe-57) and by the time-dependent perturbed angular correlation of gamma-rays (Ta-181) technique. It has been concluded from ME experiments that by exchange of Fe by Co in the nearest neighbour shell of the nuclear probe the hyperfine magnetic field acting on Fe-57 decreases by 10-12 kG. The analysis of the TDPAC experiments revealed that two different hyperfine magnetic fields: B- 1(hf)(Ta) approximate to 61 kG and B-2(hf)(Ta) approximate to 88 kG act on the Ta-181 nuclei. Both have a negative sign.


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