New fuel governed combustion synthesis and improved luminescence in nanocrystalline Cr3+ doped ZnAl2O4 particles

This paper describes the solution combustion (SCS) synthesis of nanocrystalline Cr3+ doped ZnAl2O4 (ZAC) particles using a new efficient fuel. A thorough investigation was conducted to comprehend the interaction of dopant (Cr3+) and ZnAl2O4 host matrix, as well as the influence of doping on their structural, optical, and luminescence characteristic properties. The powder samples were thoroughly characterized using XRD, UV-Visible Diffuse Reflectance, and Photoluminescence spectroscopic techniques. The XRD analysis demonstrates the formation of polycrystalline nanoparticles, as well as a decrease in crystallite size with increasing Cr3+ concentration. The band gap energy red-shifted as Cr3+ was incorporated into the host matrix. The diffuse reflectance spectra show two absorption peaks at 395 nm and 540 nm are assigned to the 4A2g -> 4T1g and 4A2g -> 4T2g characteristic transitions of Cr3+ ions. The PL emission spectrum, on the other hand, shows four distinct peaks, indicating the manifestation of Cr3+ ions in octahedral symmetry, that is, Cr3+ ions in a strong crystal field. Increases in Cr3+ concentration result in luminescence enhancement up to x = 0.07 and suppression of luminescence observed beyond that concentration. In addition, the dopant ion's Racah parameters, crystal field parameters, and local site symmetry are calculated.