Full-text resources of PSJD and other databases are now available in the new Library of Science.
Visit https://bibliotekanauki.pl
Preferences help
Polish version English version Language
enabled [disable] Abstract
Number of results

Results found: 15

Number of results on page
first rewind previous Page / 1 next fast forward last

Search results

help Sort By:

help Limit search:
first rewind previous Page / 1 next fast forward last
1
Content available remote

Neutron and X-Ray Scattering in the Studies of Metals

100%
Dobrzyński L.
|
|
vol. 96
|
issue 2
165-180
EN
Neutrons and X-rays are well established tools for studying properties of condensed matter. With the advent of synchrotron radiation facilities their high photon fluxes started to be effectively used in the fields reserved earlier for neutrons. Although the two techniques are conceptually so similar that many physical problems can be solved using either technique, there are apparent fields in which one method is superior with respect to the other one. Therefore both techniques are often needed for characterization of the material of interest. The paper concentrates on the studies of some static properties of metals and alloys. Relatively wide range of phenomena is presented, starting from structural aspects and ending on the sophisticated studies of the magnetic moment components. The paper is intended to bring a short (yet necessarily subjective and incomplete) review of what has recently been achieved by using neutrons and X-rays in metal (or more precisely - metallic states) studies.
2
Content available remote

Electronic Structure and Ordering Degree in Fe_3Al Alloy Doped with Transition Metals. Ab Initio Study

64%
Go A., Dobrzyński L.
Acta Physica Polonica A
|
2012
|
vol. 121
|
issue 5-6
1124-1127
EN
Fe_3Al alloy crystallizes in DO_3-type structure. In the perfectly ordered alloy there are two nonequivalent sublattices (A,C) and B, which are occupied by Fe atoms, whereas all D sites are taken by metalloid. Such perfect ordering is, however, difficult to achieve experimentally, and some disorder between B-D as well as (A,C)-D sublattices typically appears in real samples. This disorder modifies strongly electronic structure and magnetic properties. The aim of this contribution is to investigate total energy dependence of atomic exchange of sites between B-D and (A,C)-D positions in Fe_3Al as well as in alloys doped with transition metals using ab-initio technique. Furthermore, dependence of electronic and magnetic properties of Fe_3Al-based alloys on the crystallographic ordering is thoroughly investigated.
3
Content available remote

Inelastic Neutron Scattering in Sendust Alloy in 8-295 K Temperature Range

51%
Świderska K., Jankowska-Kisielińska J., Dobrzyński L.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 2
400-404
EN
The effects concerning magnetic and nuclear excitations in a single crystal of Sendust alloy (73.5 at.% Fe, 9.5 at.% Al, 17 at.% Si) are discussed. The excitations have been investigated by means of elastic and inelastic neutron scattering with the use of triple axis and small angle spectrometer. A few potential causes of spin wave damping in Sendust, like interactions of excitations or small-size precipitations of different compositions or directions of magnetization were disproved. It is suggested that one- and two-phonon scattering can explain observed strong increase of incoherent inelastic scattering with temperature.
4
Content available remote

Volume Effect on the Magnetism of Fe_{3-x}Cr_{x}Al

51%
Go A., Pugaczowa-Michalska M., Dobrzyński L.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 1
191-193
EN
Magnetic properties of Fe_{3-x}Cr_{x}Al alloys depend strongly on the unit cell volume. Purpose of this work is to investigate the dependence of the total and local magnetic moments on the lattice constant using the self-consistent spin-polarised TB-LMTO method.
5
Content available remote

Reconstruction of the Exchange Integrals Map of ScFe₄Al₈ Magnetic Structure

51%
Rećko K., Dobrzyński L., Waliszewski J., Szymański K.
Acta Physica Polonica A
|
2015
|
vol. 127
|
issue 2
424-426
EN
The influence of the dipolar as well as crystal field interaction as the main reasons of the noncollinearity and incommensurability of the 3d-3d-3p alloy belonging to ThMn₁₂ family is investigated. Available data on the single crystal neutron scattering experiments for ScFe₄Al₈ compound are discussed. The values and directions of the spin ordering found by magnetic diffraction are compared to that one derived from ground state configurations obtained by a simulated annealing algorithm.
6
Content available remote

Magnetic Properties of DO_{3}-Type Alloys Based on Fe_{3}Si and Fe_{3}Al

51%
Parzych G., Jankowska-Kisielinska J., Dobrzyński L.
|
|
issue 4
578-581
EN
The interest in magnetic properties of DO_{3}-type alloys stems from their ability to exhibit dependence of magnetic moments on local environment. It is shown that both, static and dynamic properties of the alloys based on Fe_{3}Si and Fe_{3}Al require further investigations. This concerns mainly the problem of selective substitution of chromium for iron, as well as spin dynamics, the latter problem is illustrated on the example of measured spin waves in Sendust.
7
Content available remote

Maximum Entropy Method in Mössbauer Spectroscopy - a Problem of Magnetic Texture

51%
Satuła D., Szymański K., Dobrzyński L.
Acta Physica Polonica A
|
2011
|
vol. 119
|
issue 1
78-80
EN
A reconstruction of the three dimensional distribution of the hyperfine magnetic field, isomer shift and texture parameter z from the Mössbauer spectra by the maximum entropy method is presented. The method was tested on the simulated spectrum consisting of two Gaussian hyperfine field distributions with different values of the texture parameters. It is shown that proper prior has to be chosen in order to arrive at the physically meaningful results.
8
Content available remote

The Magnetic Properties of GaFeO_3 by Neutron Diffraction and Mössbauer Spectroscopy

51%
Rećko K., Szymański K., Dobrzyński L., Waliszewski J.
Acta Physica Polonica A
|
2012
|
vol. 122
|
issue 2
396-399
EN
The multiferroic GaFeO_3 synthesized by a sol-gel method and conventional solid state reaction show remarkably different magnetic transition temperatures. Both samples have orthorhombic crystal structure Pc2_1n. Results of a new analysis of neutron diffraction and Mössbauer data are presented. Full agreement between parameters was achieved using the Mössbauer data as the constraints in the refinement of neutron diffraction data at low and at high temperature. Magnetic moments are reported.
9
Content available remote

Application of Bayesian Reasoning and the Maximum Entropy Method to Some Reconstruction Problems

45%
Fornalski K., Parzych G., Pylak M., Satuła D., Dobrzyński L.
|
|
issue 6
892-899
EN
The so-called Bayesian reasoning is applied whenever uncertainty has to be considered as serious factor in interpretation of results. The paper presents analysis of the impact of inaccurate data on the straight line and quadratic relation fittings. This type of analysis is particularly important when one tries to decide on the type of dependence. The paper also shows examples of the Maximum Entropy Methods applied to the reconstruction of the hyperfine parameters distribution from the measured Mössbauer spectra of GaFeO_{3} and the electron-positron momentum distribution from the positron annihilation data of Gd.
10
Content available remote

Microstructure and Magnetic Properties of Iron Oxide Nanoparticles Prepared by Wet Chemical Method

45%
Satuła D., Kalska-Szostko B., Szymański K., Dobrzyński L., Kozubowski J.
Acta Physica Polonica A
|
2008
|
vol. 114
|
issue 6
1615-1621
EN
The magnetic properties of iron oxide nanoparticles prepared by the chemical decomposition of the iron chlorides with the ratio Fe^{3+}/Fe^{2+}=2.25 were studied by means of transmission electron microscopy, X-ray diffraction and Mössbauer spectroscopy in- and without external magnetic field. The transmission electron microscopy studies show that the nanoparticles have spherical shape with diameter about 13 nm. The transmission electron microscopy and X-ray diffraction patterns are composed of lines that could be indexed within the cubic spinel structure. The room temperature Mössbauer spectrum shows the coexistence of the broad magnetically split part and superparamagnetic doublet. The in-field Mössbauer measurements carried out in the temperature range from room temperature down to 13 K show a gradual increase in the spin canting on the surface of the nanoparticles and decrease in the intensity of the superparamagnetic doublet. The sample was subjected to annealing process performed at elevated temperature in air atmosphere in order to change the microstructure of the nanoparticles and in consequence to change the magnetic properties of the sample. The annealing process leads to the decrease in the value of quadrupole splitting of the superparamagnetic doublets.
11
Content available remote

On the Crystal and Magnetic Behavior οf ScFe_{4}Al_{8} Single Crystal

39%
Rećko K., Dobrzyński L., Lemée-Cailleau M., Waliszewski J., Talik E., Suski W., Courtois P.
Acta Physica Polonica A
|
2009
|
vol. 115
|
issue 1
206-208
EN
Nuclear and magnetic properties of the ScFe_{4}Al_{8} single crystal were found to exhibit unparalleled complexity of nuclear and magnetic structures. Our previous neutron measurements revealed presence of two modulation vectors, both along [ε, ε, 0], however with different critical temperatures. Recent experiments forced us to revise our knowledge of the structural ordering in the sample. So far, the crystal structure of this alloy, being of ThMn_{12}-type, has never been questioned.
12
Content available remote

The Resistivity and Hall Effect of the Amorphous Co_{x}Ni_{70-x}Fe_{5}Si_{15}B_{10} Ribbons

39%
Perzyńska K., Biernacka M., Dobrzyński L., Malinowski A., Tarasenko S., Zaleski P.
Acta Physica Polonica A
|
2000
|
vol. 97
|
issue 5
745-748
EN
The influence of structural disorder and magnetism on the resistivity of the amorphous Co_{x}Ni_{70-x}Fe_{5}Si_{15}B_{10} ribbons was investigated. The resistivity vs. alloy composition shows parabolic-like behaviour. In the thermal behaviour, resistivities of the samples show apparent magnetic contribution. They also exhibit minima at temperatures which can be correlated with the Curie temperatures. Above T ≥ 0.5T_{C} resistivity increases linearly with increasing temperature. This effect is seemingly due to electron-phonon scattering. Obviously, the chemical and positional disorder is responsible for the major part of resistivity.
13
Content available remote

Positron Annihilation Characteristics in Zn_{1-x}Mg_{x}Se Mixed Crystals

33%
Firszt F., Szatkowski J., Męczyńska H., Łęgowski S., Saarinen K., Hautojarvi P., Plazaola A., Reniewicz H., Dobrzyński L., Chabik S.
Acta Physica Polonica A
|
1998
|
vol. 94
|
issue 2
300-304
EN
Positron annihilation characteristics as a function of composition and annealing in zinc vapour were measured and compared with photoluminescence spectra for Zn_{1-x}Mg_{x}Se mixed crystals with 0 ≤ x ≤ 0.6. The positron annihilation data show that there is a substantial number of divacancies present in the system under study. The concentration of such defects is reduced at least by the factor of two upon annealing in zinc vapour.
14
Content available remote

Investigation of Electronic Structure of Zn_{1-x}Mg_{x} Mixed Crystals by Compton Spectroscopy Method

33%
Reniewicz H., Andrejczuk A., Dobrzyński L., Rećko K., Waliszewski J., Żukowski E., Firszt F., Łęgowski S., Meczyńska H., Szatkowski J.
Acta Physica Polonica A
|
1996
|
vol. 90
|
issue 5
907-910
EN
The first experimental study of the Compton profiles of Zn_{1-x}Mg_{x}Se for x=0.25, 0.47, 0.56 mixed crystals is presented. The Compton profiles were measured with the use of the ^{241}Am radioactive source with a resolution of 0.57 a.u. The experimentally obtained Compton profiles were compared with the theoretical ones based on the free-atom model. The results are interpreted in terms of outermost electrons of Zn and Mg being promoted to the higher momentum states, and 4p-electrons of Se becoming more delocalised in a solid, being thus promoted to the lower momentum states.
15
Content available remote

Effect of Annealing in Multicomponent bcc Alloys

33%
Szymański K., Perzyńska K., Satuła D., Dobrzyński L., Zaleski P., Waliszewski J., Rećko K., Biernacka M., Olszewski W.
Acta Physica Polonica A
|
2011
|
vol. 119
|
issue 1
62-64
EN
Multicomponent single phase alloys were synthesized according to the idea of iron-average atom system. X-ray diffraction shows formation of bcc phase and traces of unidentified phase. Mössbauer spectra indicate presence of two components with different hyperfine magnetic field distributions. The high field component corresponds to the majority ferromagnetic phase. Few per cent of iron builds low field component. The dominant effect of annealing consists in an increase of the low field component.
first rewind previous Page / 1 next fast forward last
JavaScript is turned off in your web browser. Turn it on to take full advantage of this site, then refresh the page.