Defect level influenced optical properties of Eu 3+ and Tb 3+ doped in ZnO-CaAl xO y composite

Abstract

A Eu 3+/Tb 3+ doped composite material (calcium aluminate-zinc oxide) has been synthesized by the combustion process. The formation of the composite has been verified by using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Fourier transform infrared (FTIR) spectroscopy has been used to investigate the vibrations of the bands in of the material. The luminescence of the undoped composite material shows the band edge emission due to ZnO (λ exc = 355 nm) in the UV/blue and defect level emissions in the green and red. The band edge emission shows a shift toward shorter wavelength and the effect of an optical avalanche intensity when temperature is lowered (50-30 K). No effect on the defect emissions is seen. Intense fluorescence due to transitions 5D J (J = 0, 1, and 2) to the lower levels 7F J (J = 0, 1, 2, 3, 4, 5 and 6) is seen. The large intensity is attributed to contribution from the defect emission from ZnO. The same material doped with Tb 3+ instead of Eu 3+ shows that the presence or absence of ZnO has little effect. © 2012 Elsevier B.V. All rights reserved.