The effect of Tb doping on the structure and spectroscopic properties of MgAl2O4 nanopowders

In this paper, a modified sol-gel method was employed to prepare nanostructured MgAl₂O₄ spinel powders doped with Tb³⁺ ions and thermally treated at 700 and 1000 °C for 3 h. The structural properties of the prepared at 700 and 1000 °C powders where characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). According to obtained XRD patterns the formation of single-phase spinels after calcination was confirmed. The XRD analyses demonstrated that the powders were single-phase spinel nanopowders with high crystallite dispersion. The Rietveld method was applied to calculate lattice parameters. The averaged spinel particle size was determined to be ∼10 nm for calcination at 700 °C and ∼20 nm at 1000 °C. The emission and excitation spectra measured at room and low temperature (77 K) for the samples calcined at 700 and 1000 °C demonstrated characteristic spectra of Tb³⁺ ions. The effect of MgAl₂O₄:Tb³⁺ grain sizes on luminescence properties was noticed.