The yellow color of silver-containing zeolite A

Roland Seifert, Andreas Kunzmann and Gion Calzaferri
Department of Chemistry and Biochemistry, University of Bern, Freiestrasse 3, CH-3000 Bern 9, Switzerland


Colorless in the hydrated state, silver-containing zeolite A turns yellow to brick-red upon activation. This color change is reversible with respect to desorption/adsorption of water. The reason for this phenomenon, which has been known since 1962, was unclear until now. It is now shown that a charge transfer transition from the oxygen atoms of the zeolite lattice to the empty 5s orbital of the silver ions is responsible for the yellow coloring.

published in: Angew. Chemie 1998, 110, 1603; int. Edition 1998, 37, 1521.

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