Synthesis of Eu3+ doped magnesium aluminate spinel via combustion method: Investigation of thermodynamics, crystal structure, microstructure, and luminescence properties

In the current research, the rare earth-doped magnesium aluminate (MgAl₂O₄:Eu³⁺) spinels were produced by the combustion synthesis method. The employment of thermodynamic calculations revealed that the combustion approach is a proper way to synthesize MgAl₂O₄:Eu³⁺ material by urea fuel, although this procedure was fulfilled at 500°C, the final temperature will be around 2030°C. The x-ray and FT-IR spectra confirmed the successful formation of spinels, while it was shown that the calcination procedure results in a significant increase of crystallinity. On the other hand, it was interestingly seen that the addition of large amounts of Eu³⁺dopant (10 wt%) suppresses the crystallinity. The MAUD calculations interestingly revealed that the increase of Eu³⁺ dopant from 1 to 10 wt% leads to the increase of MgO and Al₂O₃ impurities. The related microstructural evaluations revealed that the particle size of the synthesized powders is mostly less than 40 nm which shows the superiority of combustion synthesis over other commercial methods. Also, the broadening of XRD peaks confirmed the formation of nano-sized powder. The photoluminescence (PL) characterizations showed that doping of MgAl₂O₄ with 7 wt% Eu³⁺ brings the most intensive emission properties at the wavelengths of 592 and 617 nm.