title: Internal architecture of coffin-shaped ZSM-5 zeolite crystals with hourglass contrast unravelled by focused ion beam-assisted transmission electron microscopy.
abstract: Optical microscopy, focused ion beam and transmission electron microscopy are combined to study the internal architecture in a coffin-shaped ZSM-5 crystal showing an hourglass contrast in optical microscopy. Based on parallel lamellas from different positions in the crystal, the orientation relationships between the intergrowth components of the crystal are studied and the internal architecture and growth mechanism are illustrated. The crystal is found to contain two pyramid-like components aside from a central component. Both pyramid-like components are rotated by 90° along the common c-axis and with respect to the central component while the interfaces between the components show local zig-zag feature, the latter indicating variations in relative growth velocity of the two components. The pyramid-like intergrowth components are larger and come closer to one another in the middle of the crystal than at the edges, but they do not connect. A model of multisite nucleation and growth of 90° intergrowth components is proposed.
authors.affiliation: School of Electronic and Information Engineering, Xi'an Jiaotong University, Xi'an, 710049, People's Republic of China.
authors.forename: J
authors.initials: J
authors.lastname: Lu
authors.affiliation: COK, KU Leuven, Kasteelpark Arenberg 23, B-3001, Heverlee, Belgium.
authors.forename: E
authors.initials: E
authors.lastname: Bartholomeeusen
authors.affiliation: COK, KU Leuven, Kasteelpark Arenberg 23, B-3001, Heverlee, Belgium.
authors.forename: B F
authors.initials: BF
authors.lastname: Sels
authors.affiliation: EMAT, University of Antwerp, Groenenborgerlaan 171, B-2020, Antwerp, Belgium.
authors.forename: D
authors.initials: D
authors.lastname: Schryvers
keywords: Focused ion beam; ZSM-5; intergrowth; internal architecture; rotational boundary; transmission electron microscopy