A concise study on luminescence of dealuminated faujasite and the formation of nanoclusters in the zeolite host structure

Abstract

Strong cathodoluminescence (CL) in the blue spectral range was observed in dealuminated Faujasite (DAF) zeolite-Y. CL and photoluminescence (PL) measurements are discussed on the background of the formation of nanoclusters in the open cages of the zeolite host structure. DAF was mixed with a SnCl/sub 2/ solution and subsequently dried under stirring and annealed in H/sub 2/- or O/sub 2/-ambient to establish metallic Sn or semiconducting SnO/sub 2/ clusters in the zeolite pores. Samples with various nominal weight ratios were prepared, i.e. SnO/sub 2//DAF=0.15-0.8 and Sn/DAF=0.1-0.6. X-ray powder diffraction (XRD) analysis shows that the nominal incorporation of Sn or SnO/sub 2/ resulted in weak reduction of the lattice constants. At 77 K all samples exhibit a strong CL signal in the blue spectral range, which was clearly visible by the eye, but no significant spectral properties which might be attributed to a nanocluster formation could be deduced. PL measurements at 77 K do not give significant verification of a cluster formation, too. One can conclude that the strong CL mainly originates from the DAF and that the incorporation of Sn or SnO/sub 2/ clusters was either rather poor and/or has no significant influence on the luminescence behavior.