Synthesis of BaAl2O4: Eu2+/Li+ co-doped spinel: study of crystal structure, microstructure, and photoluminescence characteristics

Abstract

In this research BaAl₂O₄: Eu²⁺/Li⁺ luminescent materials were synthesized through a facile solid-state approach at 1100 °C. To study the effect of Li⁺ ions, different amounts of LiCl were used within the synthesis of BaAl₂O₄-based compounds. The crystal structural, microstructure, surface characteristics, and photoluminescence properties were scrutinized by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), Fourier transform infrared (FTIR) analyses. It was shown that the addition of LiCl flux material results in very slight changes in the crystallographic properties of BaAl₂O₄ crystal structure while the use of LiCl has severely reduced the average particle size from about 225 nm to 120 nm. Upon the excitation procedure at the wavelength of 343 nm, BaAl₂O₄: Eu²⁺ shows a strong and wide emission in the range of 435–610 nm that is attributed to the 4f⁶5d¹-4f⁷ transition of Eu²⁺. The highest emission occurs when 2.5 wt% LiCl was utilized as flux material. Moreover, through the employment of XPS characterization, it was proved that the addition of Li⁺ ions causes higher binding energies of elements and improvement of crystallization.