Abstract:
Samples of pure zinc aluminates (ZnAl2O4) and doped ZnAl2O4 with both lead (Pb2+)
at different ratios (0, 0.5, 1, 1.5, 2, and 2.5% mol) and a constant amount of lanthanum
(La3+: 1% mol), were prepared by the citrate sol-gel technique, and then annealed at
900°C for 2h. To study the structural, optical, and thermal properties; different
characterization methods were used, such as powder X-ray diffraction (XRD),
scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX),
differential scanning calorimetry (DSC-TG), Fourier transform infrared spectroscopy
(FTIR) and Raman spectroscopy. Analysis by XRD revealed the presence, for all
samples, of the cubic, single-phase ZnAl2O4, without any impurity phases, with a
crystallites size between 19 and 25 nm. These results were confirmed using FTIR and
Raman spectroscopy. Also UV–VIS spectra indicated that the band-gap of the doped
samples decreases and exhibits a red shift with the increase of Pb2+ ion concentration.
In addition, a photocatalytic study for different samples of ZnAl2O4 showed that they
could be used as photocatalysts and good adsorbents for the degradation of a
Hexamethyl Crystallized Violet (HCV) dye in an aqueous solution.
Photoluminescence spectra of pure, doped, and co-doped ZnAl2O4 show emission
peaks located at 432, 510, and 566 nm
