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Titolo:
Structure refinement of the silicon carbide polytypes 4H and 6H: unambiguous determination of the refinement parameters
Autore:
Bauer, A; Reischauer, P; Krausslich, J; Schell, N; Matz, W; Goetz, K;
Indirizzi:
Univ Jena, Inst Opt & Quantum Elect, D-07743 Jena, Germany Univ Jena Jena Germany D-07743 pt & Quantum Elect, D-07743 Jena, Germany Rossendorf Inc, Forschungszentrum Rossendorf EV, D-01314 Dresden, Germany Rossendorf Inc Dresden Germany D-01314 dorf EV, D-01314 Dresden, Germany
Titolo Testata:
ACTA CRYSTALLOGRAPHICA SECTION A
, volume: 57, anno: 2001,
parte:, 1
pagine: 60 - 67
SICI:
0108-7673(200101)57:<60:SROTSC>2.0.ZU;2-N
Fonte:
ISI
Lingua:
ENG
Soggetto:
X-RAY-DIFFRACTION; PHASES;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
Citazioni:
15
Recensione:
Indirizzi per estratti:
Indirizzo: Bauer, A Univ Jena, Inst Opt & Quantum Elect, Max Wien Pl 1, D-07743 Jena,Germany Univ Jena Max Wien Pl 1 Jena Germany D-07743 07743 Jena, Germany
Citazione:
A. Bauer et al., "Structure refinement of the silicon carbide polytypes 4H and 6H: unambiguous determination of the refinement parameters", ACT CRYST A, 57, 2001, pp. 60-67

Abstract

The atomic positions of the silicon carbide (SiC) polytypes 6H and 4H differ slightly from an ideal tetrahedron. These small deviations can be investigated by X-ray diffraction of so-called 'quasiforbidden' reflections, which are very sensitive with respect to the extremely small variations in the structure. Nevertheless, an unambiguous calculation of the refinement parameters from the absolute values of the structure factors of the 'quasiforbidden' reflections is not possible. In the case of SiC-4H, there are two and,in the case of SiC-6H, six different structure models, which yield the same absolute values of the structure factors. In order to distinguish betweenthese models, additional phase information about the measured reflections is needed. To achieve this, Renninger-scan (psi -scan) profiles in the vicinity of three-beam cases are used. These experimentally measured psi -scansare compared with theoretical calculated profiles for each model. Another method to distinguish the different models is to compare the bond lengths between atoms of the two polytypes, which have equivalent vicinities. For both SiC-4H and SiC-6H, an unambiguous determination of the structure refinement parameters was possible.

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Documento generato il 30/09/20 alle ore 09:27:00