Cathodoluminescent characteristics of sm-doped ZnAl2O4 nanostructured powders

Cathodoluminescent (CL) powders of zinc aluminate activated with samarium ions have been prepared by a co-precipitation chemical process. Different doping concentrations in the start mixture and sintering temperatures for the precipitated powder were studied. It was observed that the crystalline characteristics of the powders depend upon the sintering temperature. For temperatures higher than 450 degreesC, the powders presented the cubic spinel phase with a lattice parameter value of 8.0756 Angstrom, and grain sizes from 50 to 100 urn with semispherical shape. The CL emission spectra showed broad bands localized at 564, 602, 644, and 703 nm associated with (4)G(5/2) --> H-6(5/2), (4)G(5/2) --> H-6(7/2), (4)G(5/2) --> H-6(9/2) and 4G(5/2) --> H-6(11/12) transitions in the Sm3+ ions, respectively. Concentration quenching of the cathodoluminescence occurred at about 4.26 at% of the activator (Sm) concentration inside the sintered powders. (C) 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.