Photoluminescence of Manganese-doped ZnAl2O4 nanophosphors

Manganese-doped zinc aluminate spinel (ZnAl2O4:Mn) phosphor nanopowders were prepared by the sol-gel process. X-ray diffraction revealed that the dried powders were amorphous and converted into ZnAl2O4 structure followed firing at above 600 degrees C. On firing at 600 degrees-1000 degrees C, the doped ZnAl2O4 powders had the average crystallite sizes of 12 similar to 20 nm. SEM investigation exhibited the phosphor powders had primary particle size of around 20 similar to 25 nm and narrow size-distribution after calcining at 1000 degrees C. The luminescence properties of Mn-doped ZnAl2O4 nanophosphors were characterized by excitation and emission spectra. Photoluminescence spectra exhibited prominent green emission bands centered at 512 nm, corresponding to the typical T-4(1)((4)G)-(6)A(1)(S-6) transition of Mn2+ ions under an excitation wavelength of 458 nm. The luminescence intensity increased with increasing the Mn content up to 3.0 mol%, but decreased significantly as doping of above 4.0 mol%. (C) 2010 Elsevier B.V. All rights reserved.