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Wyszukujesz frazę "Malczewski, D." wg kryterium: Autor


Wyświetlanie 1-6 z 6
Tytuł:
57Fe Mössbauer spectroscopy and X-ray diffraction study of gadolinites REE2Fe2+Be2Si2O10 from Lower Silesia (Poland) and Ytterby (Sweden)
Autorzy:
Malczewski, D.
Powiązania:
https://bibliotekanauki.pl/articles/148858.pdf
Data publikacji:
2003
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
gadolinite
Mössbauer spectroscopy
X-ray diffraction
Opis:
This paper reports the results of 57Fe Mössbauer spectroscopy, X-ray diffraction (XRD) and gamma-ray spectroscopy studies of partially metamict gadolinites from Szklarska Poręba and Zimnik (Lower Silesia, Poland), a fully metamict gadolinite sample from Ytterby (Sweden) and a crystalline sample obtained after annealing of a fragment of the sample from Ytterby at 1373 K in an argon atmosphere. Both fully metamict and crystalline gadolinite show divalent iron exclusively in octahedral coordination. Changes of the amplitudes ratio of high energy to low energy absorption peaks from Fe2+ quadrupole doublets are strictly correlated with calculated absorbed alpha-dose and the metamictization stages of the gadolinite specimens. In this respect, one of the samples is in conflict with the estimated radiation dose based on age and radionuclide concentrations. In this case, Mössbauer spectroscopy shows that the sample had to be naturally annealed over geologic time.
Źródło:
Nukleonika; 2003, 48,suppl.1; 41-44
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Erratum to “Preliminary results of 57Fe Mössbauer spectroscopy of metamict samarskite after one-hour high temperature annealing in argon” [Nukleonika 2017;62(2):141-144]
Autorzy:
Malczewski, D.
Grabias, A.
Powiązania:
https://bibliotekanauki.pl/articles/147593.pdf
Data publikacji:
2017
Wydawca:
Instytut Chemii i Techniki Jądrowej
Źródło:
Nukleonika; 2017, 62, 4; 311
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Preliminary results of 57Fe Mössbauer spectroscopy of metamict samarskite after one-hour high temperature annealing in argon
Autorzy:
Malczewski, D.
Grabias, A.
Powiązania:
https://bibliotekanauki.pl/articles/146552.pdf
Data publikacji:
2017
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
samarskite
metamict minerals
Mössbauer spectroscopy
recrystallization
Opis:
The preliminary results of 57Fe Mössbauer spectroscopy and X-ray diffraction (XRD) of fully metamict samarskite dated at ~1500 Ma, which absorbed -dose of 6.5 × 1017 α-decay mg–1, are reported after one-hour annealing at 673, 873, 1173 and 1373 K in argon atmosphere. Metamict minerals contain radioactive elements that degrade their crystal structures over geological time. All the Mössbauer spectra obtained can be fitted to two quadrupole doublets assigned to Fe2+ and Fe3+ in octahedral positions. The relative contribution of Fe2+ (Fe2+/Fe) reaches a minimum of 0.10 at 1173 K.
Źródło:
Nukleonika; 2017, 62, 2; 141-144
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
57Fe Mössbauer study of stilpnomelane and associated chlorite from Polish granite pegmatites
Autorzy:
Malczewski, D.
Popiel, E.
Sitarek, A.
Powiązania:
https://bibliotekanauki.pl/articles/147222.pdf
Data publikacji:
2004
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
stilpnomelane
chlorite
Mössbauer spectroscopy
Opis:
This paper reports the results of 57Fe Mössbauer study of stilpnomelane K0.6Fe6(Si8Al)(O,OH)27 .2H2O from Żółkiewka (Lower Silesia, Poland). Stilpnomelane in paragenesis with chlorite, tourmaline, claevelandite and zeolites has been found in granite pegmatites in quarries at Żółkiewka. The samples of naturally weathered stilpnomelane and chlorite from the same fragment of rock were also studied. The Mössbauer spectrum of an untreated sample could be fitted to two Fe2+ doublets and two Fe3+ doublets. The Fe2+ doublets have similar isomer shifts, but they distinctly differ in values of quadrupole splittings. Ferric iron, octahedrally coordinated occurs in three different environments represented by two doublets. The first of them, assigned to combined M1 + M2 positions and the second one assigned to M3 site with parameters IS = 0.36 mm/s and QS = 2.07 mm/s is visible in the spectra up to 880°C. This doublet is characteristic of stilpnomelane and can be regarded as a "fingerprint" of this mineral. After heating at 200°C, the relative content of Fe2+, ÓFe2+/ÓFe, decreases to 0.22 what means a 50% decrease in comparison to the initial value observed in the untreated sample. At about 1000°C, complete breakdown of the stilpnomelane structure takes place and the Mössbauer spectrum consists of two sextets and two ferric doublets. Abnormally high content of Fe2+ in naturally weathered stilpnomelane (0.70) comparing to the untreated sample of stilpnomelane (0.45) indicates that the sample had to be subjected to hydrothermal processes operating locally. Almost the same contents of divalent iron and hyperfine parameters of Fe2+ and Fe3+ doublets in weathered stilpnomelane and associated chlorite suggest that the process of chlorite transformation into stilpnomelane seems to be very probable.
Źródło:
Nukleonika; 2004, 49,suppl.3; 43-48
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
57Fe Mössbauer spectroscopy of annealed metamict davidite
Autorzy:
Malczewski, D.
Frąckowiak, J.
Galuskin, E.
Powiązania:
https://bibliotekanauki.pl/articles/148337.pdf
Data publikacji:
2007
Wydawca:
Instytut Chemii i Techniki Jądrowej
Tematy:
davidite
metamict minerals
recrystallization
Mössbauer spectroscopy
Opis:
This paper reports preliminary results of 57Fe Mössbauer spectroscopy and X-ray diffraction (XRD) studies of metamict davidite samples (La,Ce,Ca,Th)(Y,U,Fe)(Ti,Fe,Mn)20(O,OH)38 after high temperature annealing in an argon atmosphere. The Mössbauer spectra show a gradual decrease of quadrupole splitting and line width values of an Fe3+ doublet with increasing annealing temperature. Rather unexpected feature of these spectra for an Fe2+ doublet is a considerable increase of the line width with progressive crystallinity and a simultaneous decrease of both quadrupole splitting and isomer shift values. Changes of the hyperfine parameters as a function of the annealing temperature appeared as sensitive indicators of the thermal recrystallization process of metamict davidite similar to metamict silicates.
Źródło:
Nukleonika; 2007, 52, supl. 1; 81-84
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Identification of iron-bearing minerals in basalts and pillow lavas of the Kaczawa Mountains using 57Fe Mössbauer spectroscopy
Autorzy:
Malczewski, D.
Jeleń, M.
Żaba, J.
Błachowski, A.
Ruebenbauer, K.
Dziurowicz, M.
Powiązania:
https://bibliotekanauki.pl/articles/146452.pdf
Data publikacji:
2017
Wydawca:
Instytut Chemii i Techniki Jądrowej
Opis:
The Kaczawa Mountains along with the Kaczawa foothill comprise a complicated geological unit that is called the Kaczawa metamorphic (Sudetes, SW Poland). The aim of our work was to identify the iron-bearing minerals in samples of basalts and pillow lavas from the Kaczawa metamorphic using 57Fe Mössbauer spectroscopy. Based on the preliminary results, the Fe3+/Fe2+ ratio in the samples was determined.
Źródło:
Nukleonika; 2017, 62, 2; 145-148
0029-5922
1508-5791
Pojawia się w:
Nukleonika
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

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