Luminescence properties of ZnGa2O4 and ZnAl2O4 spinels doped with Eu3+ and Tb3+ ions

Spinel-type ZnGa2O4 and ZnAl2O4 powders doped with Eu3+ and Tb3+ ions, including dual doping, have been prepared by solid phase reactions and by deposition from chemical solutions. XRD analysis demonstrates the high quality of spinel grains constituting the powder. The luminescence shows that the rare earth ions are incorporated in the defect regions at the grain boundaries. The emission spectra of the samples with europium are characterized by an intense emission in red region due to the D-5(0) -> F-7(1,2) transitions of Eu3+ ions, whereas in the case of terbium the highest intensity corresponds to the green emission due to the D-5(4) -> F-7(5) transitions of Tb3+ ions. The possibility to change the color of the emission from green to red by the variation of Tb and Eu doping concentration is demonstrated. (C) 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim