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Wyszukujesz frazę "powder diffractometry" wg kryterium: Temat


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Tytuł:
Rentgenowska dyfraktometria proszkowa w badaniach zabytkowych obiektów. Nowe możliwości badawcze na Wydziale Chemii UJ
Autorzy:
Grzesiak, Marta
Oszajca, Marcin
Rafalska-Łasocha, Alicja
Łasocha, Wiesław
Powiązania:
https://bibliotekanauki.pl/articles/636614.pdf
Data publikacji:
2011
Wydawca:
Uniwersytet Jagielloński. Wydawnictwo Uniwersytetu Jagiellońskiego
Tematy:
X-ray powder diffractometry
chemical analysis
Resurrected Christ from Bodzentyn
investigations of historic-objects
Opis:
Powder diffraction techniques in studies of historical objects can be applied to the investigations of such substances as pigments, corrosion products of metals and other crystalline artistic materials. Unlike techniques such as X-ray fluorescence (XRF) and other methods of chemical analysis that provide information on elemental composition, XRPD enables the identification and differentiation of materials with similar or even identical chemical compositions. Shell and limestone, are chemically the same (calcium carbonate), but the atoms are arranged differently in each of them. It would be difficult to tell these materials apart using elemental analysis. Some techniques, however, such as X-ray diffraction (XRD), provide information on the way atoms are arranged in a given sample and thanks to this knowledge it is possible to detect which sample contain limestone an which contain shell. As other examples one can mention several pigments; e.g., two types of lead-tin yellow, Pb2SnO4 and PbSnO3 polymorphic modifications of TiO2, or different kinds of verdigris. Precise information on the substance used in an artwork is sometimes of great importance in the dating and authentication a work of art, and in studying the origin of historical materials and in characterization of the artist’s workshop. Moreover, a description of secondary changes in the phase composition enables the study of the signs and causes of damage produced by environmental conditions and is vital to the proper conservation of the object, whether through preventive measures or restorative treatment. X-ray diffraction analysis requires a very small sample (in micro-diffraction measurements, often much less than the size of a pinhead). Moreover an identification of the investigated materials can be performed with the use of already present reference powder diffraction data (PDF Files), which are prepared and distributed by the International Centre for Diffraction Data (Pennsylvania, USA). In this paper the results of the investigations of a green paint in the Gothic panel painting Resurrected Christ from Bodzentyn (Chrystus Zmartwychwstały z Bodzentyna are presented as an example of application of micro-diffraction analysis to study the pigments. Obtained results allowed identification of lead tin yellow type I (Pb2SnO4, PDF[24-0589]), hydrocerussite ((PbCO3)2Pb(OH)2, PDF[13-131]), malachite (Cu(OH)2CuCO3, PDF[56-0001]) and cynabar (HgS, PDF [42-1408]).
Źródło:
Opuscula Musealia; 2011, 19; 25-36
0239-9989
2084-3852
Pojawia się w:
Opuscula Musealia
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Nowe metody w badaniach struktur polikryształów
New methods in investigations of polycrystalline materials
Autorzy:
Łasocha, W.
Luberda-Durnaś, K.
Powiązania:
https://bibliotekanauki.pl/articles/172430.pdf
Data publikacji:
2014
Wydawca:
Polskie Towarzystwo Chemiczne
Tematy:
dyfraktometria proszkowa
wskaźnikowanie obrazów dyfrakcyjnych
rozkład obrazu dyfrakcyjnego na intensywności
uściślanie struktur metodą Rietvelda
metoda badań strukturalnych
powder diffractometry
indexing of diffraction patterns
powder diffraction pattern decomposition
structure refinement using the Rietveld method
methods of structural studies
Opis:
In this chapter, information on good laboratory practice in the field of structural powder diffractometry has been collected. The authors attempt to describe how to plan a measurement, how to find the cell parameters, how to build a model of the structure, and how to refine and verify it. There are many methods and procedures which lead to solving a crystal structure. However, the experience of recent years shows that, in the case of many materials, an investigator has to attempt the problem of structure solution using many different methods. The software is easily available (from ‘trial and error’ or classic to sophisticated modern approaches), as is a lot of good equipment. On the other hand, the complexity of the structures studied using powder diffraction methods is continually increasing. No description of any methods of research other than diffraction techniques is presented. We have also focused on polycrystalline materials. Amorphous substances and methods using the formalism of ‘pair distribution functions’ are beyond the scope of this paper. New methods of structural studies (including algorithms from research described in the literature, even if their applicability has been relatively slight) were treated with particular attention. In addition to the description of methods, we also collected some useful (in our opinion) information about available software and crystallographic databases.
Źródło:
Wiadomości Chemiczne; 2014, 68, 5-6; 507-543
0043-5104
2300-0295
Pojawia się w:
Wiadomości Chemiczne
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-2 z 2

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