title: Explanation of the stacking disorder in the β-phase of Pigment Red 170.
abstract: The β-phase of Pigment Red 170, C26H22N4O4, which is used industrially for the colouration of plastics, crystallizes in a layer structure with stacking disorder. The disorder is characterized by a lateral translational shift between the layers with a component ty of either +0.421 or -0.421. Order-disorder (OD) theory is used to derive the possible stacking sequences. Extensive lattice-energy minimizations were carried out on a large set of structural models with different stacking sequences, containing up to 2688 atoms. These calculations were used to determine the actual local structures and to derive the stacking probabilities. It is shown that local structures and energies depend not only on the arrangement of neighbouring layers, but also next-neighbouring layers. Large models with 100 layers were constructed according to the derived stacking probabilities. The diffraction patterns simulated from those models are in good agreement with the experimental single-crystal and powder diffraction patterns. Electron diffraction investigation on a nanocrystalline industrial sample revealed the same disorder. Hence the lattice-energy minimizations are able to explain the disorder and the diffuse scattering.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Strasse 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Jaroslav L
authors.initials: JL
authors.lastname: Teteruk
authors.affiliation: Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Strasse 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Glinnemann
authors.affiliation: Institut für Physikalische Chemie, Gutenberg-Universität, Welderweg 11, D-55128 Mainz, Germany.
authors.forename: Tatiana E
authors.initials: TE
authors.lastname: Gorelik
authors.affiliation: Department of Chemistry, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Anthony
authors.initials: A
authors.lastname: Linden
authors.affiliation: Institut für Anorganische und Analytische Chemie, Goethe-Universität, Max-von-Laue-Strasse 7, D-60438 Frankfurt am Main, Germany.
authors.forename: Martin U
authors.initials: MU
authors.lastname: Schmidt
keywords: Pigment Red 170; disorder; electron diffraction; lattice-energy minimization; local structure; order–disorder theory