title: Core-shell strain structure of zeolite microcrystals.
abstract: Zeolites are crystalline aluminosilicate minerals featuring a network of 0.3-1.5-nm-wide pores, used in industry as catalysts for hydrocarbon interconversion, ion exchangers, molecular sieves and adsorbents. For improved applications, it is highly useful to study the distribution of internal local strains because they sensitively affect the rates of adsorption and diffusion of guest molecules within zeolites. Here, we report the observation of an unusual triangular deformation field distribution in ZSM-5 zeolites by coherent X-ray diffraction imaging, showing the presence of a strain within the crystal arising from the heterogeneous core-shell structure, which is supported by finite element model calculation and confirmed by fluorescence measurement. The shell is composed of H-ZSM-5 with intrinsic negative thermal expansion whereas the core exhibits a different thermal expansion behaviour due to the presence of organic template residues, which usually remain when the starting materials are insufficiently calcined. Engineering such strain effects could have a major impact on the design of future catalysts.
authors.affiliation: Department of Physics, Sogang University, Seoul 121-742, Korea.
authors.forename: Wonsuk
authors.initials: W
authors.lastname: Cha
authors.forename: Nak Cheon
authors.initials: NC
authors.lastname: Jeong
authors.forename: Sanghoon
authors.initials: S
authors.lastname: Song
authors.forename: Hyun-jun
authors.initials: HJ
authors.lastname: Park
authors.forename: Tung Cao
authors.initials: TC
authors.lastname: Thanh Pham
authors.forename: Ross
authors.initials: R
authors.lastname: Harder
authors.forename: Bobae
authors.initials: B
authors.lastname: Lim
authors.forename: Gang
authors.initials: G
authors.lastname: Xiong
authors.forename: Docheon
authors.initials: D
authors.lastname: Ahn
authors.forename: Ian
authors.initials: I
authors.lastname: McNulty
authors.forename: Jungho
authors.initials: J
authors.lastname: Kim
authors.forename: Kyung Byung
authors.initials: KB
authors.lastname: Yoon
authors.forename: Ian K
authors.initials: IK
authors.lastname: Robinson
authors.forename: Hyunjung
authors.initials: H
authors.lastname: Kim
mesh_terms: D018360:Crystallography, X-Ray; D055616:Microtechnology; D013696:Temperature; D014961:X-Ray Diffraction; D017641:Zeolites / Q000737:chemistry*
chemical_list: D017641:Zeolites