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Wyświetlanie 1-12 z 12
Tytuł:
Mössbauer Investigation of Spin Arrangements in $Er_{2-x}Ce_xFe_{14}B$
Autorzy:
Bogacz, B.
Pędziwiatr, A.
Powiązania:
https://bibliotekanauki.pl/articles/1811580.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
75.25.+z
Opis:
It was theoretically postulated earlier that in compounds $Er_{2-x}Ce_{x}Fe_{14}B$ it may be possible to observe not only axial and planar spin arrangements but also a conical one. In order to experimentally verify this hypothesis, $\text{}^{57}Fe$ Mössbauer spectroscopy analysis was used to study the polycrystalline compounds $Er_{2-x}Ce_{x}Fe_{14}B$ in the postulated composition region (x = 1.0, 1.1, 1.2, 1.3) in the wide range of temperatures. The obtained experimental data do not clearly support the suggestion of conical arrangement occurrence in the postulated compositions. They indicate that such phenomenon may be shifted towards higher Ce content.
Źródło:
Acta Physica Polonica A; 2008, 114, 6; 1509-1516
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin arrangement diagrams for Er2-xRxFe14B (R = Y, Ce) obtained with Mössbauer spectroscopy and phenomenological model
Autorzy:
Pędziwiatr, A.
Bogacz, B.
Gargula, R.
Powiązania:
https://bibliotekanauki.pl/articles/148797.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
Mössbauer effect
permanent magnet materials
spin diagrams
spin reorientation
Opis:
Two isostructural series of polycrystalline compounds: Er2-xYxFe14B and Er2-xCexFe14B have been studied by 57Fe Mössbauer spectroscopy in the temperature range 80-370 K. The spin reorientation phenomenon (a transition from basal plane to axial easy magnetisation direction) has been studied extensively by a narrow step temperature scanning in the vicinity of the transition. Using the procedure of subtracting the Mössbauer spectra taken for the same compound at different temperatures, it was possible to follow the influence of transition on the shape of spectra. From this procedure it was concluded that in the region of transition each subspectrum splits into two Zeeman sextets, which are characterised by different hyperfine magnetic fields and quadrupole splittings. The consistent way of describing the Mössbauer spectra was proposed. The spin reorientation temperatures have been established for all compositions and compared with the values obtained from theoretical calculations of spin orientation angle based on phenomenological model. The spin arrangement diagrams have been constructed.
Źródło:
Nukleonika; 2003, 48,suppl.1; 59-63
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mössbauer studies of spin reorientations in Er2-xGdxFe14B
Autorzy:
Wojciechowska, A.
Bogacz, B.
Pędziwiatr, A.
Powiązania:
https://bibliotekanauki.pl/articles/147233.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
Mössbauer effect
spin reorientation
Opis:
The Er2 xGdxFe14B (x = 0.5, 1.0, 1.5) polycrystalline compounds have been investigated with 57Fe Mössbauer spectroscopy in the 80 330 K temperature range. The spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature scanning in the neighbourhood of the spin reorientation temperature. From the analysis of the spectra it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterized by different hyperfine magnetic fields and quadrupole splittings. A consistent way of describing the Mössbauer spectra in the wide range of temperatures was proposed. The composition and temperature dependencies of hyperfine interaction parameters and subspectra contributions were derived from experimental spectra. The transition temperatures were determined for all the compounds studied.
Źródło:
Nukleonika; 2004, 49,suppl.3; 71-73
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Crystal electric field parameters determination for R2Fe14B compounds based on Yamada - Kato model
Autorzy:
Bogacz, B. F.
Pędziwiatr, A. T.
Powiązania:
https://bibliotekanauki.pl/articles/147342.pdf
Data publikacji:
2013
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
crystal electric field parameters
model Yamada-Kato
Mössbauer effect
permanent magnet materials
spin reorientation
Opis:
Semi-empirical model developed by Yamada-Kato enables calculation of magnetic spin directions for R2Fe14B compounds, based on minimization of free energy, and - in further steps - determination of spin reorientation temperatures for transitions from basal plane to axial easy magnetization direction. In our study, this model has been successfully used to determine crystal field and exchange field parameters for Er2-xCexFe14B compounds based on spin reorientation temperatures obtained experimentally from Mössbauer measurements.
Źródło:
Nukleonika; 2013, 58, 1; 31-33
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin reorientation phenomena in Er2-xRxFe14B (R = Gd, Th) – Mössbauer and calorimetric study
Autorzy:
Wojciechowska, A.
Pędziwiatr, A.
Bogacz, B.
Wróbel, S.
Powiązania:
https://bibliotekanauki.pl/articles/148335.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
Mössbauer effect
spin reorientation
Opis:
The Er2 xGdxFe14B (x = 0.5, 1.0, 1.5) and Er2 xThxFe14B (x = 0.0, 0.5, 1.0, 1.5, 2.0) polycrystalline compounds have been investigated with 57Fe Mössbauer spectroscopy and differential scanning calorimetry (DSC). A comparison of results related to spin reorientation phenomena obtained for Gd- and Th-substituted compounds is presented in this paper. Spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature scanning in the neighbourhood of the spin reorientation temperature, TSR. From the analysis of Mössbauer spectra, it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterised by different hyperfine magnetic fields and quadrupole splittings. A consistent way of fitting the spectra in the wide range of temperatures was proposed. The composition and temperature dependencies of hyperfine interaction parameters and subspectra contributions were derived from fits and the transition temperatures were determined for all the compounds studied. DSC studies proved that the spin reorientations were accompanied by thermal effects for all compositions of the Gd- and for x = 0.5 of the Th-series. Transformation enthalpy and TSR were determined from these studies and the two-stage character of transition was confirmed. Magnetic spin arrangement diagrams for R = Th and Gd series were constructed and compared using combined data obtained with both methods.
Źródło:
Nukleonika; 2007, 52, supl. 1; 77-79
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Mössbauer and Magnetometric Studies of Spin Reorientations in Er$\text{}_{2-x}$Th$\text{}_{x}$Fe$\text{}_{14}$B
Autorzy:
Wojciechowska, A.
Bogacz, B. F.
Pędziwiatr, A. T.
Powiązania:
https://bibliotekanauki.pl/articles/2046203.pdf
Data publikacji:
2006-03
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
75.25.+z
Opis:
The Er$\text{}_{2-x}$Th$\text{}_{x}$Fe$\text{}_{14}$B (x=0.5, 1.0, 1.5) polycrystalline compounds have been investigated with $\text{}^{57}$Fe Mössbauer spectroscopy in the 50-330 K temperature range and magnetometry in the temperature range of 4.2-340 K. Initial magnetization vs. temperature measurements allowed us to establish the temperature regions of reorientations and also the Curie temperatures of the compounds. The spin reorientation phenomena (changes from planar to axial spin arrangements) have been studied extensively by a narrow step temperature Mössbauer scanning in the vicinity of the spin reorientation temperatures. From the analysis of the obtained Mössbauer spectra it was deduced that in the region of transition each subspectrum was split into two Zeeman sextets, which were characterised by different hyperfine magnetic fields and quadrupole splittings. A consistent way of describing the Mössbauer spectra in the wide range of temperatures was proposed. The composition and temperature dependences of hyperfine interaction parameters and subspectra contributions were derived from experimental spectra. The transition temperatures were determined for all the compounds studied and the spin phase diagram was constructed.
Źródło:
Acta Physica Polonica A; 2006, 109, 3; 427-432
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin Reorientation Studies in Nd$\text{}_{2}$Fe$\text{}_{14-x}$Si$\text{}_{x}$B (0
Autorzy:
Gargula, R.
Pędziwiatr, A.
Bogacz, B.
Wróbel, S.
Bartolomé, J.
Stankiewicz, J.
Powiązania:
https://bibliotekanauki.pl/articles/2030427.pdf
Data publikacji:
2002-02
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
75.50.Ww
76.80.+y
64.60.-i
Opis:
Nd$\text{}_{2}$Fe$\text{}_{14-x}$Si$\text{}_{x}$B (x=0.25, 0.5, 0.75, 1.0, 1.5, 2.0) intermetallic compounds were investigated by magnetometry, $\text{}^{57}$Fe Mössbauer effect, electric resistivity, and differential scanning calorimetry mainly in the vicinity of the spin reorientation temperature, T$\text{}_{SR}$. The Curie temperature, T$\text{}_{C}$, and T$\text{}_{SR}$ were determined for different compositions and the spin phase diagram was constructed. $\text{}^{57}$Fe Mössbauer spectra showed noticeable changes in the reorientation region. For temperatures above the transition, the spectra were analysed using 6 Zeeman patterns associated with 6 inequivalent crystal sites in Nd$\text{}_{2}$Fe$\text{}_{14}$B according to site occupations (16k$\text{}_{1}$:16k$\text{}_{2}$:8j$\text{}_{1}$:8j$\text{}_{2}$:4c:4e). In the transition region, 12 subspectra had to be incorporated in the analysis. Electric resistivity measurements showed a typical metallic behaviour with no anomalies in the magnetic transition region. Differential scanning calorimetry measurements revealed broad endothermic two stage peaks around T$\text{}_{SR}$.
Źródło:
Acta Physica Polonica A; 2002, 101, 2; 289-294
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Search for canted spin arrangement in Er2-xTbxFe14B with Mössbauer spectroscopy
Autorzy:
Kurzydło, P. M.
Bogacz, B. F.
Pędziwiatr, A. T.
Oleszak, D.
Przewoźnik, J.
Powiązania:
https://bibliotekanauki.pl/articles/147036.pdf
Data publikacji:
2015
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
Mössbauer effect
permanent magnet materials
spin diagrams
spin reorientation
Opis:
The materials studied were polycrystalline compounds Er2-xTbxFe14B (x = 0.1, 0.2, 0.3, 0.4) which crystallize in a tetragonal lattice and display a variety of spin arrangements. The compounds have been measured with 57Fe Mössbauer spectroscopy over the temperature range 80–320 K in order to investigate the spin reorientation processes. Each compound was studied in a wide temperature range, with precise Mössbauer scanning in the vicinity of the transition. The set of spectra obtained for a given compound was analyzed using simultaneous fi tting procedure to investigate the infl uence of the transition on the shape of the spectra. The fi tting program was specifi ed to analyze the transition according to the ‘two state model’: spins fl ip abruptly from initial angle to fi nal arrangement (90° angle). Obtained results suggest that spin reorientation process cannot be described using only the mentioned above model. Additional computer simulations based on the Yamada–Kato model were conducted to determine temperature range and the type of spin alignments in the vicinity of the transition. These theoretical results supported by spectra analysis suggest the existence of intermediate (canted) spin arrangements in the studied compounds. The spin arrangement diagram was constructed.
Źródło:
Nukleonika; 2015, 60, 1; 93-96
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spin reorientation process in Tm2–xHoxFe14B : analysis of conical arrangement based on Mössbauer spectra
Autorzy:
Kurzydło, P. M.
Pędziwiatr, A. T.
Bogacz, B. F.
Przewoźnik, J.
Oleszak, D.
Powiązania:
https://bibliotekanauki.pl/articles/148120.pdf
Data publikacji:
2017
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
permanent magnetic materials
Mössbauer effect
spin reorientation
spin diagrams
Opis:
The spin reorientation process in the Tm2–xHoxFe14B series of compounds was studied using 57Fe Mössbauer spectroscopy over the temperature range 5.2–320 K with a focus on the analysis of conical spin arrangement. Each compound was studied by precise Mössbauer scanning in the vicinity of the transition and during the transition. By applying computer simulations based on the simplified Yamada-Kato model, as well as on some literature data for R2Fe14B (R = Tm, Ho) compounds, the above series was selected for studies as it contains compounds with different spin arrangements (axial, planar, conical). It was a crucial requirement for obtaining unambiguous angular dependences when applying a simultaneous fitting procedure of Mössbauer spectra. Such an extended procedure was applied which allowed the temperature dependence of the angle describing the position of the magnetization vector to be obtained. The results were compared with those from theoretical simulations. The spin arrangement diagram was constructed. A conical spin arrangement was confirmed over a wide temperature range.
Źródło:
Nukleonika; 2017, 62, 2; 123-127
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Influence of Carbon on Spin Reorientation Processes in $Er_{2-x}R_xFe_{14}C$ (R~=~Gd, Pr) - Mössbauer and Magnetometric Studies
Autorzy:
Pędziwiatr, A.
Krawiec, K.
Bogacz, B.
Kapusta, Cz.
Przewoźnik, J.
Kaczorowski, D.
Talik, E.
Powiązania:
https://bibliotekanauki.pl/articles/1506592.pdf
Data publikacji:
2011-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
76.80.+y
75.25.-j
75.50.-y
75.50.Bb
Opis:
The $Er_{2-x}R_{x}Fe_{14}C$ (R=Gd, Pr) polycrystalline compounds have been synthesized and investigated with $\text{}^{57}Fe$ Mössbauer spectroscopy and magnetic measurements. The spin reorientation phenomena were studied extensively by narrow step temperature scanning in the neighborhood of the spin reorientation temperature. Obtained Mössbauer spectra were analyzed using a procedure of simultaneous fitting and the transmission integral approach. Consistent description of Mössbauer spectra were obtained, temperature and composition dependencies of hyperfine interaction parameters and subspectra contributions were derived from fits and the transition temperatures were determined for all the compounds studied. Initial magnetization versus temperature measurements (in zero and non-zero external field) for $Er_{2-x}Gd_{x}Fe_{14}C$ compounds allowed to establish the temperature regions of reorientation, change of magnetization value during the transition process. The results obtained with different methods were analyzed and the spin arrangement diagrams were constructed. Data obtained for $Er_{2-x}Gd_{x}Fe_{14}C$ were compared with those for $Er_{2-x}Gd_{x}Fe_{14}B$ series.
Źródło:
Acta Physica Polonica A; 2011, 119, 1; 48-51
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Decomposition of hydrogen perodixe - kinetics and review of chosen catalysts
Autorzy:
Pędziwiatr, P.
Mikołajczyk, F.
Zawadzki, D.
Mikołajczyk, K.
Bedka, A.
Powiązania:
https://bibliotekanauki.pl/articles/105966.pdf
Data publikacji:
2018
Wydawca:
Centrum Badań i Innowacji Pro-Akademia
Tematy:
decomposition
hydrogen peroxide
catalysis
catalysts
silver catalyst
photocatalysis
dekompozycja
nadtlenek wodoru
kataliza
katalizatory srebrowe
fotokataliza
Opis:
Hydrogen peroxide is a chemical used in oxidation reactions, treatment of various inorganic and organic pollutants, bleaching processes in pulp, paper and textile industries and for various disinfection applications. It is a monopropellant, which, when purified, is self-decomposing at high temperatures or when a catalyst is present. Decomposing to yield only oxygen and water(disproportionation), hydrogen peroxide is one of the cleanest, most versatile chemicals available. The catalytic decomposition of hydrogen peroxide allows the use of various catalysts that will increase the rate of decomposition. Comparison and description of the most commonly used catalysts were presented in this review.
Źródło:
Acta Innovations; 2018, 26; 45-52
2300-5599
Pojawia się w:
Acta Innovations
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ukraina pasją przyrodnika pisana
Autorzy:
Pedziwiatr, K.
Antkowiak, M.
Lubkowska, R.
Jakubowska, A.
Sajkowska, Z.
Powiązania:
https://bibliotekanauki.pl/articles/845188.pdf
Data publikacji:
2013
Wydawca:
Polskie Towarzystwo Przyrodników im. Kopernika
Tematy:
Ukraina
miasta
Cherson
Naga Przystan
obwod chersonski
walory przyrodnicze
obszary wiejskie
rezerwat Askania Nowa
dolina Dniepru
Rezerwat Biosfery Morza Czarnego
polwysep Drowskaja Kosa
Zatoka Tendrowska
fauna
flora
Źródło:
Wszechświat; 2013, 114, 04-06
0043-9592
Pojawia się w:
Wszechświat
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-12 z 12

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