title: Variation of large-scale regularity in modulated structures of Ca2CoSi2O7 studied by a simulation method.
abstract: The period of two-dimensional modulation in Ca2CoSi2O7 varies with temperature (q = 0.285-1/3). The change in the modulated structure with the variation of q has been clarified by the construction of the structures using various q values and the modulation amplitudes determined at 293 K [q = 0.2913 (1), tetragonal]. The features of the modulated structures are characterized by the formation of CaO6 polyhedra and the variable distribution of bundles along the c-axis, composed of four arrays of CaO6 polyhedra and an array of CoO4 tetrahedra. The formation of octagonal arrangements of the bundles is a typical feature of the structures in the incommensurate phase. Large-scale regularities with sizes much larger than the modulation wavelength are also formed in the structures.
authors.affiliation: Department of Life Science, Himeji Institute of Technology, Koto 3-2-1, Kamigori, Akogun, Hyogo 678-1297, Japan.
authors.forename: Katsuhiro
authors.initials: K
authors.lastname: Kusaka
authors.forename: Kenji
authors.initials: K
authors.lastname: Hagiya
authors.forename: Masaaki
authors.initials: M
authors.lastname: Ohmasa
authors.forename: Kazuaki
authors.initials: K
authors.lastname: Iishi