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Wyszukujesz frazę "Wiertel, M." wg kryterium: Autor


Tytuł:
$\text{}^{57}Fe$ Hyperfine Interactions in the $Sc(Fe_{1-x}Ni_x)_2$ Laves Phases Synthesized under High Pressure
Autorzy:
Wiertel, M.
Surowiec, Z.
Budzyński, M.
Tsvyashchenko, A.
Powiązania:
https://bibliotekanauki.pl/articles/1811581.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
77.80.Bh
75.30.Kz
07.35.+k
Opis:
The structural and microscopic magnetic properties of the pseudobinary $Sc(Fe_{1-x}Ni_x)_2$ system prepared under high pressure of 8 GPa were studied by X-ray diffraction and Mössbauer measurements in the range of 0.0 ≤ x ≤ 0.60. The samples for 0.0 ≤ x ≤ 0.10 have the hexagonal C14-type structure and those for 0.30 ≤ x ≤ 0.60 crystallize in the C15-type structure. Both the magnetic hyperfine field on $\text{}^{57}Fe$ and the Curie temperature decrease with the increasing Ni content and the system becomes paramagnetic for x ≈ 0.60 at room temperature. The form and temperature dependences of the Mössbauer spectra for 0.40 ≤ x ≤ 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. It is interesting that $T_C$ for the compounds obtained under high pressure are by about 100 K smaller in comparison with those for the isostructural samples produced under normal pressure even though interatomic distances are practically equal in the both types of compounds.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1517-1527
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An application of Mössbauer spectroscopy in the studies of iron - molybdenum silica mesoporous materials
Autorzy:
Surowiec, Z.
Wiertel, M.
Marynowska, A.
Gac, W.
Zawadzki, W.
Powiązania:
https://bibliotekanauki.pl/articles/147814.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
iron
MCM-41 porous silica
molybdenum
Mössbauer effect
superparamagnetic nanoparticles
Opis:
Iron-molybdenum silica mesoporous materials were obtained by the application of direct hydrothermal method. Four samples with different metal contents relative to silica were investigated. Incorporation of iron and molybdenum ions in the synthesis stage led to structural changes of the MCM-41 support. With an increasing metals content, cylindrical pores of silica initially transformed into bottle-ink type pores, and then into the slit-like ones. Mössbauer spectroscopy investigations indicated that Fe ions were embedded in the silica walls and then formed nanosized crystallites in the pores. Superparamagnetic phase was observed at liquid nitrogen temperature.
Źródło:
Nukleonika; 2013, 58, 1; 137-141
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Charge Transfer Dynamics in Atom-Metal Surface Collisions
Autorzy:
Wiertel, M.
Taranko, R.
Taranko, E.
Powiązania:
https://bibliotekanauki.pl/articles/2011189.pdf
Data publikacji:
1999-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.Rf
78.70.-g
82.65.Pa
Opis:
We study the charge exchange in atom-metal collisions in the framework of the generalized time-dependent Anderson-Newns model. The electron correlations and correlated hopping are treated within the mean-field approximation. The resulting one-particle model with an effective spin-dependent atom-surface coupling is used to study the charge transfer in scattering of Na and Li atoms on metal surfaces. It is shown that the effective occupation dependent atom-surface coupling influences mainly the expectation values for producing positive, neutral, and negative particles for small work functions and high atom velocities. It is also shown that the temperature dependence of these expectation values is more visible, especially for magnetic solutions.
Źródło:
Acta Physica Polonica A; 1999, 96, 6; 769-783
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of an Adsorbed Atom on Resonant Charge Exchange in Atom Scattering on Metal Surfaces
Autorzy:
Taranko, R.
Taranko, E.
Wiertel, M.
Powiązania:
https://bibliotekanauki.pl/articles/2035749.pdf
Data publikacji:
2003-05
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
79.20.-m
82.65.+r
34.70.+e
Opis:
A simple model describing resonant charge transfer between the free-electron metal surface and an atom colliding with it at some distance from another adsorbed atom is presented. The negative ionization probability of a scattered atom is studied within the time-dependent Anderson-Newns model and the time-evolution operator approach. With appropriate models for the considered system, the ionization probability is shown to oscillate with the distance between the adsorbed atom and the collision point of the scattered atom with the metal surface. These oscillations are results of the indirect interaction between the adsorbed and the scattered atoms due to the coupling of both atoms with the metal energy band.
Źródło:
Acta Physica Polonica A; 2003, 103, 5; 483-497
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of Sc substitution for Y on structural properties and hyperfine interactions in Y1-xScxFe2 compounds
Autorzy:
Budzyński, M.
Sarzyński, J.
Wiertel, M.
Surowiec, Z.
Powiązania:
https://bibliotekanauki.pl/articles/148816.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
hyperfine interactions
Mössbauer effect
quasibinary Laves phase
Y1-xScxFe2
Opis:
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.
Źródło:
Nukleonika; 2003, 48,suppl.1; 79-83
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effect of the substitution of Ti for Y on structural properties and hyperfine interactions in Y1-xTixFe2 compounds
Autorzy:
Surowiec, Z.
Sarzyński, J.
Budzyński, M.
Wiertel, M.
Powiązania:
https://bibliotekanauki.pl/articles/971534.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
hyperfine interactions
Mössbauer effect
quasibinary Laves phase
Y1 xTixFe2
Opis:
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.
Źródło:
Nukleonika; 2004, 49,suppl.3; 17-21
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Impact of Impulse Shot Peening Parameters on Properties of Stainless Steel Surface
Autorzy:
Wiertel, M.
Zaleski, K.
Gorgol, M.
Skoczylas, A.
Zaleski, R.
Powiązania:
https://bibliotekanauki.pl/articles/1033967.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.65.-b
81.20.Wk
62.20.Qp
61.72.-y
78.70.Bj
Opis:
Shot peening was applied to austenitic stainless steel 1.4541 (EN). The surface treatment was performed at various impact energies E, impact densities j and ball diameters D. This resulted in improved microhardness, which increases monotonically with the increase of E, j and 1/D. However, its changes with E and j achieve saturation at about 400 HV0.1. On the contrary, no saturation is observed in the investigated range for 1/D. In the un-shot peened 1.4541 (EN) steel, the lifetime component of low intensity was found with use of positron annihilation lifetime spectroscopy (PALS). It corresponds to positron annihilation from delocalized state of positrons in bulk. In the shot peened samples the bulk component is no longer observed. Instead, two types of defects can be identified: vacancy-like defects coupled with edge dislocations and vacancies or their small clusters (consisting 3÷5 vacancies). The results of PALS and hardness testing do not correspond very well, especially in the case of the samples shot peened with balls of varying diameters. The most probable reason for this are different depth profiles of both methods. It seems that the defects, which are responsible for the increase of static microhardness above 400 HV0.1 are located mostly below the surface layer penetrated by positrons.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1611-1615
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of annealing temperature on structural and magnetic properties of MnFe2O4 nanoparticles
Autorzy:
Surowiec, Z.
Wiertel, M.
Gac, W.
Budzyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/146127.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
manganese ferrite
MCM-41 porous silica
Mössbauer effect
superparamagnetic nanoparticles
Opis:
Nanoparticles of manganese ferrite were obtained by the impregnation of highly ordered mesoporous MCM-41 silica support. The investigated sample contained 20% wt. Fe. The obtained nanocrystallites were strongly dispersed in silica matrix and their size was about 2 nm. The sample annealing at 500°C led to increase of particle size to about 5 nm. The Mössbauer spectroscopy investigations performed at room temperature show on occurrence of MnFe2O4 nanoparticle in superparamagnetic state for the sample annealed in all temperatures. The coexistence of superparamagnetic and ferromagnetic phase was observed at liquid nitrogen temperature. The sample annealed at 400°C and 500 °C has bigger manganese ferrite particle and better crystallized structure. One can assign them the discrete hyperfi ne magnetic field components.
Źródło:
Nukleonika; 2015, 60, 1; 137-141
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic and structural properties of Sc(Fe1−xSix)2 Laves phases studied by Mössbauer spectroscopy and neutron diffraction
Autorzy:
Wiertel, M.
Surowiec, Z.
Budzyński, M.
Sarzyński, J.
Beskrovnyi, A. I.
Powiązania:
https://bibliotekanauki.pl/articles/147702.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
hyperfine fields
Mössbauer effect
neutron diffraction
quasibinary Laves phase
Opis:
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.
Źródło:
Nukleonika; 2015, 60, 1; 155-160
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Magnetic Nanoparticles in MCM-41 Type Mesoporous Silica
Autorzy:
Surowiec, Z.
Bierska-Piech, B.
Wiertel, M.
Budzyński, M.
Goworek, J.
Powiązania:
https://bibliotekanauki.pl/articles/1811605.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.67.Bf
81.07.Bc
76.80.+y
Opis:
Structural phase transformations and magnetic properties of mesoporous MCM-41 template modified with iron and nickel salts were studied by nitrogen physisorption, X-ray diffraction, Mössbauer spectroscopy and transmission electron microscopy. The FeNi-oxide or the bimetallic crystal structure is formed for low and high Ni concentrations, respectively. The average size of nanoparticles is about 10 nm. About 70% of particles exist in a superparamagnetic state at room temperature.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1605-1613
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mechanical Properties of the Stellite 6 Cobalt Alloy Implanted with Nitrogen Ions
Autorzy:
Budzyński, P.
Kamiński, M.
Wiertel, M.
Pyszniak, K.
Droździel, A.
Powiązania:
https://bibliotekanauki.pl/articles/1030127.pdf
Data publikacji:
2017-08
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
68.55.Ln
62.20.Qp
61.82.Bg
61.80.-x
Opis:
The effect of nitrogen ion implantation on Stellite 6 cobalt alloy was investigated. In this research, cobalt alloy was implanted with 65 keV nitrogen ions at the fluence of (1÷10)×10¹⁶ N⁺/cm². The distribution of implanted nitrogen ions and vacancies produced by them was calculated using the SRIM program. The surface morphology was examined and the elemental analysis was performed using scanning electron microscopy, energy dispersive X-ray spectroscopy and grazing incidence X-ray diffraction. The wear tests were conducted with the use of the pin-on-disc method. The results demonstrate that implantation with nitrogen ions significantly reduces the friction factor and wear. The friction coefficient of the implanted sample at the fluence of 1×10¹⁷ N⁺/cm² increased to the values characteristic of an unimplanted sample after 5000 measurement cycles. The depth of the worn trace was about 2.0 μm. This implies that the thickness of the layer modified by the implantation process is ≈2.0 μm and exceeds the initial range of the implanted ions by an order of magnitude. This is referred to as a long-range implantation effect. The investigations have shown that the long-range effect is caused by movement of not only implanted nitrogen atoms but also carbon dopant atoms towards the friction zone. Diffusion of carbon atoms has been documented here for the first time. Furthermore, the increased content of oxygen atoms on the track bottom indicates a dominant oxidative wear of the Stellite samples after nitrogen implantation with the energy 65 keV and the fluences of 5×10¹⁶ and 10¹⁷ N⁺/cm².
Źródło:
Acta Physica Polonica A; 2017, 132, 2; 203-205
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mössbauer and X-ray Diffraction Studies of Zr$\text{}_{1-x}$Ti$\text{}_{x}$Fe$\text{}_{2}$ Laves Phase Compounds
Autorzy:
Budzyński, M.
Sarzyński, J.
Surowiec, Z.
Wiertel, M.
Powiązania:
https://bibliotekanauki.pl/articles/2028966.pdf
Data publikacji:
2001-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
31.30.Gs
77.80.Bh
75.30.Kz
Opis:
Mössbauer spectroscopy of $\text{}^{57}$Fe and X-ray diffraction measurements in the Zr$\text{}_{1-x}$Ti$\text{}_{x}$Fe$\text{}_{2}$ 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≤x≤0.5 a mixture of both structures occurs. The investigated compounds are paramagnetic at RT for x>0.80 and magnetic for x
Źródło:
Acta Physica Polonica A; 2001, 100, 5; 717-722
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mössbauer study of magnetite nanowire in MCM-41 type mesoporous silica templates
Autorzy:
Surowiec, Z.
Goworek, J.
Ryczkowski, J.
Budzyński, M.
Wiertel, M.
Sarzyński, J.
Powiązania:
https://bibliotekanauki.pl/articles/148203.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
hyperfine interactions
Mössbauer effect
MCM-41 silica
nanowires
Opis:
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.
Źródło:
Nukleonika; 2007, 52, supl. 1; 33-36
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in $MnFe_2O_4$/MCM-41 Nanocomposite
Autorzy:
Wiertel, M.
Surowiec, Z.
Gac, W.
Budzyński, M.
Powiązania:
https://bibliotekanauki.pl/articles/1339369.pdf
Data publikacji:
2014-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.70.Bj
34.80.Lx
78.67.Bf
62.23.Pq
68.43.-h
75.50.Gg
78.47.D-
Opis:
In the paper results of studies of $MnFe_2O_4$/MCM-41 nanocomposites have been presented. The influence of manganese ferrite loading on changes of porous properties of mesoporous MCM-41 structure was studied by means of $N_2$ sorption/desorption method and positron annihilation lifetime spectroscopy. Disappearance of the longest-lived ortho-positronium component ($τ_5$) of pure MCM-41 mesoporous material in the positron annihilation lifetime spectra of $MnFe_2O_4$/MCM-41 measured in vacuum is a result of either o-Ps quenching or the Ps inhibition mechanism. Filling of pores in the studied nanocomposites by air at ambient pressure causes partial reappearance of the ($τ_5$) component except for the sample with maximum ferrite content. Both the ($τ_5$) component lifetime and intensity are suppressed together with increasing $MnFe_2O_4$ content by chemical quenching and inhibition of Ps formation occur. Observed anti-quenching effect of air is a result of two processes: neutralization of some surface active centres acting as inhibitors and considerably weaker paramagnetic quenching by $O_2$ molecules.
Źródło:
Acta Physica Polonica A; 2014, 125, 3; 793-797
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Positron Annihilation in Magnetite Nanopowders Prepared by Co-Precipitation Method
Autorzy:
Durak, K.
Wiertel, M.
Surowiec, Z.
Miaskowski, A.
Powiązania:
https://bibliotekanauki.pl/articles/1033944.pdf
Data publikacji:
2017-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
81.07.Wx
47.65.Cb
78.70.Bj
61.72.J-
61.72.Mm
68.37.Hk
Opis:
Nanosized iron oxide powders are materials considered with regard to its application in medical therapy called hyperthermia. Magnetite nanopowders with crystallite size varying from 6.6 to 11.8 nm have been prepared by the co-precipitation method. In this study a change of a crystallite size is driven mainly by varying of initial pH of water ammonia solution in which a process of magnetite precipitation runs. Crystallographic structures and phase composition obtained samples and the size of magnetite nanoparticles were determined by X-ray diffraction method. Positron lifetime spectroscopy has been used to assess defectiveness of microstructure. Experimental positron annihilation spectra were successfully resolved into three lifetime components. It appears that from point of view of microstructure the defects concentrations in studied nanopowder samples are very high which causes a saturation of positron trapping.
Źródło:
Acta Physica Polonica A; 2017, 132, 5; 1593-1597
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł

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