Transformation of refractory ceramic MgAl₂O₄ into blue light emitting nanomaterials by Sr²⁺/Cr³⁺ activation

The current research aims at manipulation of physical properties of spinel MgAl₂O₄ by substitution of Sr²⁺ cations at tetrahedral and Cr³⁺ at orthogonal-sites. Synthesized materials were studied by XRD, TGA, SEM, EDX and UV–visible, diffuse reflectance and photoluminescence spectroscopy. A series of Sr²⁺ and Cr³⁺ doped derivatives with the general formula Mg_1-xSr_xAl_2-yCr_yO₄ (where x, y = 0.2, 0.4, 0.6, 0.8 and 1.0) have been produced and investigated using the co precipitation technique. Although strain in the cubic crystal structure of magnesium aluminate spinel was seen upon doping due to Sr²⁺'s higher cationic radius, the structure remained reserved (spinel) for low dopant concentration (x, y = 0.2, 0.4, 0.6). The behavior of activator ions Cr³⁺ in these derivatives is supposed to be altered due to change in site occupancy. Due to presence of antisites defects activator ions; structural, optical, thermal, electrical properties of MgAl₂O₄ material were modified.