title: Structural phase transition and related electronic properties in quasi-one-dimensional (NbSe4)(10/3)I.
abstract: The real crystal structure of the (NbSe4)(10/3)I charge density wave (CDW) compound is studied by simulation of the X-ray diffuse scattering. The average structure of the low-temperature twinned phase is determined and the phase transition is attributed to the formation of a CDW. The diffuse streaking, present in X-ray diffraction patterns above and below the transition at T = 282 K, is shown to be a projection of diffuse concentric rings perpendicular to the c* direction. The simulated patterns, based on a mismatch model between infinite NbSe4 chains, correlated by I atoms, are in good accordance with the experimental patterns. In addition to the experiments, the electronic properties of the high- and the low-temperature phases are calculated with the extended Hückel tight-binding method. The Fermi surfaces of the average structures above and below the phase transition appear very similar. Their shapes support a nesting instability and a CDW formation. The weak incommensurate CDW satellites, present below the phase transition, are at 100 K properly described by a modulation wavevector q = [0.06 (1), 0, 0.55 (1)].
authors.affiliation: Institute of Materials Science, University of Silesia, 75 Pułku Piechoty 1a, Chorzów 41500, Poland.
authors.forename: Maciej
authors.initials: M
authors.lastname: Zubko
authors.forename: Joachim
authors.initials: J
authors.lastname: Kusz
authors.forename: Albert
authors.initials: A
authors.lastname: Prodan
authors.forename: Sašo
authors.initials: S
authors.lastname: Šturm
authors.forename: Herman J P
authors.initials: HJ
authors.lastname: van Midden
authors.forename: J Craig
authors.initials: JC
authors.lastname: Bennett
authors.forename: Grzegorz
authors.initials: G
authors.lastname: Dubin
authors.forename: Erik
authors.initials: E
authors.lastname: Zupanič
authors.forename: Horst
authors.initials: H
authors.lastname: Böhm
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D007455:Iodine / Q000737:chemistry*; D015394:Molecular Structure; D009556:Niobium / Q000737:chemistry*; D044367:Phase Transition; D012643:Selenium / Q000737:chemistry*; D013696:Temperature
chemical_list: D009556:Niobium; D007455:Iodine; D012643:Selenium
keywords: charge density waves; diffuse scattering; one-dimensional structures