ZnAl2O4: Ce3+ phosphors: Study of Crystal Structure, Microstructure, Photoluminescence Properties and Efficient Adsorption of Congo Red Dye

In this work, Ce-doped ZnAl2O4: x% Ce (x = 1-5 mol) particles have been synthesized via the facile co-precipitation approach. The effect of calcination temperature on microstructures and luminescence specifications as well as the adsorption properties for removal of Congo red (CR) have been scrutinized in detail. The results of X-ray diffraction spectra revealed that the temperature of heat treatment is a critical preparation factor affecting the formation of ZnAl2O4 pure phase and its crystallite size. It was concluded that the increase of annealing temperature from 600 degrees C to 1000 degrees C gives rise to the growth of crystallite size from 3.8 nm to 13.7 nm, respectively. The adsorption characterizations reveal that the removal efficiency of CR after 50 min for the (10 ppm) solution reaches 83.88% while with the raise of initial concentration to 40 ppm, dramatically reduces the removal efficiency to 51.94%. Also, it was shown that the pseudo-second-order model predicts well the adsorption behavior of CR. The photoluminescence spectra demonstrated that due to the optically allowed transactions of 4f(1)5d(0)-4f(0)5d(1), the highest excitation peak of ZnAl2O4: Ce phosphor occurs at 273 nm, considered as the applicable phosphors for being combined with UV emitted LEDs. It was found that the concentration of Ce ions affects the intensity of photoluminescence behavior. Correspondingly, due to the trapping of the exited electrons by the unstable structure of Ce ions, the high quantities of the rare earth elements result in the suppression of the intensity of F-2(5/2)- F-2(7/2) emission bands. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

Ce-doped ZnAl2O4: x% Ce particles were synthesized and their properties were studied, showing that the calcination temperature significantly affects microstructures and luminescence characteristics, while the concentration of Ce ions influences photoluminescence behavior intensity.