title: Direct Observation of Luminescent Silver Clusters Confined in Faujasite Zeolites.
abstract: One of the ultimate goals in the study of metal clusters is the correlation between the atomic-scale organization and their physicochemical properties. However, direct observation of the atomic organization of such minuscule metal clusters is heavily hindered by radiation damage imposed by the different characterization techniques. We present direct evidence of the structural arrangement, at an atomic level, of luminescent silver species stabilized in faujasite (FAU) zeolites using aberration-corrected scanning transmission electron microscopy. Two different silver clusters were identified in Ag-FAU zeolites, a trinuclear silver species associated with green emission and a tetranuclear silver species related to yellow emission. By combining direct imaging with complementary information obtained from X-ray powder diffraction and Rietveld analysis, we were able to elucidate the main differences at an atomic scale between luminescent (heat-treated) and nonluminescent (cation-exchanged) Ag-FAU zeolites. It is expected that such insights will trigger the directed synthesis of functional metal nanocluster-zeolite composites with tailored luminescent properties.
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors.forename: Thomas
authors.initials: T
authors.lastname: Altantzis
authors.forename: Eduardo
authors.initials: E
authors.lastname: Coutino-Gonzalez
authors.forename: Wouter
authors.initials: W
authors.lastname: Baekelant
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors.forename: Gerardo T
authors.initials: GT
authors.lastname: Martinez
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors.forename: Artem M
authors.initials: AM
authors.lastname: Abakumov
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors.forename: Gustaaf Van
authors.initials: GV
authors.lastname: Tendeloo
authors.forename: Maarten B J
authors.initials: MB
authors.lastname: Roeffaers
authors.affiliation: EMAT, University of Antwerp , Groenenborgerlaan 171, B-2020 Antwerpen, Belgium.
authors.forename: Sara
authors.initials: S
authors.lastname: Bals
authors.affiliation: RIES, Hokkaido University , N20W10, Kita-Ward Sapporo 001-0020, Japan.
authors.forename: Johan
authors.initials: J
authors.lastname: Hofkens
keywords: HAADF-STEM; Rietveld analysis; nanoporous materials; novel phosphors; self-assembly