title: Order, disorder and structural modulations in Bi-Fe-W-O-Br Sillén-Aurivillius intergrowths.
abstract: Transmission electron microscopy observations on a new complex oxybromide with nominal composition Bi(4)Fe(1/3)W(2/3)O(8)Br, heated at high temperature, reveal the transformation of its basic structure yielding two types of crystals. The first crystal type shows ordered and disordered extended defects leading to a new family of intergrowths between one Sillén block and n Aurivillius blocks and occasionally between one Aurivillius block and n Sillén blocks. The second type presents a compositionally modulated structure, determined by electron diffraction, with an average composition Bi(4)Fe(1/2)W(1/2)O(8 - delta)Br and unit-cell parameters a = (1/gamma) 3.8, b = 3.8, c = 14.5 A (gamma = 0.10-0.15) in the superspace group Immm[(1 - gamma)00] no. 71.1.
authors.affiliation: Departamento Química Inorgánica, Fac. CC. Químicas, Universidad Complutense, E-28040, Madrid, Spain. d.avila@fz-juelich.de
authors.forename: David
authors.initials: D
authors.lastname: Avila-Brande
authors.forename: Angel R
authors.initials: AR
authors.lastname: Landa-Cánovas
authors.forename: L Carlos
authors.initials: LC
authors.lastname: Otero-Díaz