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Independent q and 2q Distortions in the Incommensurately Modulated Low-Temperature Structure of NiTa2Se7

Titelangaben

Lüdecke, Jens ; Schneider, Martin ; van Smaalen, Sander:
Independent q and 2q Distortions in the Incommensurately Modulated Low-Temperature Structure of NiTa2Se7.
In: Journal of Solid State Chemistry. Bd. 153 (2000) Heft 1 . - S. 152-157.
ISSN 0022-4596
DOI: 10.1006/jssc.2000.8766

Abstract

The modulated low-temperature structure of NiTa1.98Nb0.02Se7 has been determined by X-ray diffraction using synchrotron radiation. The superspace group of the modulated structure at 15 K is C2/m (0, qb, 0) s0 with qb=0.483(2). The lattice parameters were determined to a=13.807(6) Å, b=3.483(1) Å, c=18.564(11) Å, and β=108.95(4)° with Z=4. Satellite reflections up to second order were measured. Refinement with first- and second-order harmonic components of the modulation functions converged to R=0.059. The first-order harmonic was found predominantly on the double chain of Ni and Se2 atoms. Shifts were found parallel to the Full-size image (<1 K) and Full-size image (<1 K) axes, in good agreement with earlier investigations. The major part of the second harmonic was found on the Ta2 atoms, with amplitudes of secondary importance on the surrounding Se atoms. Shifts of the Ta2 atoms were found parallel to Full-size image (<1 K), thus forming a longitudinal wave. It is argued that the modulations according to the first-order and the second-order harmonics should be considered as independent CDW's.

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Publikationsform: Artikel in einer Zeitschrift
Begutachteter Beitrag: Ja
Keywords: incommensurate structures; charge density waves; phase transitions
Institutionen der Universität: Fakultäten > Fakultät für Mathematik, Physik und Informatik > Fachgruppe Materialwissenschaften > Lehrstuhl Kristallographie
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Fachgruppe Materialwissenschaften > Lehrstuhl Kristallographie > Lehrstuhl Kristallographie - Univ.-Prof. Dr. Sander van Smaalen
Fakultäten
Fakultäten > Fakultät für Mathematik, Physik und Informatik
Fakultäten > Fakultät für Mathematik, Physik und Informatik > Fachgruppe Materialwissenschaften
Titel an der UBT entstanden: Ja
Themengebiete aus DDC: 500 Naturwissenschaften und Mathematik > 530 Physik
Eingestellt am: 23 Mär 2016 07:22
Letzte Änderung: 23 Mär 2016 07:22
URI: https://eref.uni-bayreuth.de/id/eprint/32002