engleski

Structural properties and photoluminescence of nanocrystalline gahnite doped with titanium

Zinc aluminate, ZnAl2O4 (gahnite), has been widely known as a mineral and also as a ceramic and catalytic material. It is also a semiconductor, as well as a suitable host material for transition metal cations and rare earth cations providing luminescence, which makes it applicable for various optoelectronic devices. To the best of our knowledge, there is no literature data on studies of Ti-doped gahnite reported by other authors. A series of Ti-doped gahnite samples with doping levels of 0, 1.8, 3.8, 5.4 and 11.6 at% in relation to Al were prepared by a sol-gel technique followed by thermal treatment. The samples were characterized by X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), electron paramagnetic spectroscopy (EPR), UV-vis reflectance spectroscopy and photoluminescence (PL) measurements. Diffraction patterns showed that samples possessed a spinel-type structure. Diffraction lines were broadened which suggested that samples were nanocrystalline. EPR spectroscopy indicated that titanium was present as Ti4+ ion in the doped samples, while results of UV-vis reflectance spectroscopy evidenced that Ti4+ was situated on octahedral cation site in the gahnite structure. The structure of all prepared samples was refined by the Rietveld method, simultaneously with the size-strain analysis. TEM investigations showed that samples contained evenly shaped particles of about 20 nm in size. Ti-doped gahnite samples showed a strong UV absorption, and blue photoluminescence under UV excitation. The PL intensity was strongly dependent on Ti-doping level.

Ti-doped zinc aluminate; sol-gel processing; X-ray powder diffraction; Rietveld refinement; transmission electron microscopy; luminescence

nije evidentirano