Cost effective way of tuning physical properties of MgAl2O4 spinel nanomaterials by Sr+2/Mn2+ cations doped at the T-Sites

The oxide host systems in use to date have very complicated crystalline phases and obtaining the pure phase requires specific synthesis procedures and high temperatures. Secondly, the expensive and bigger rare earth ions add up to the additional costs and their accommodation in the lattice becomes a difficult task. This leads to the deterioration of the properties of host material due to the formation of secondary phases. The current project aims at the synthesis and study of the physical properties of dielectric spinel magnesium aluminate host doped at tetrahedral sites with Sr2+/Mn2+ as an alternative simple and cost-effective oxide host. Mg1-xSrxAl2O4 (x = 0.0-1.0) and Sr2+/Mn2+ co-doped derivatives having general formula Mg1-x-ySrxMnyAl2O4 (x = 0.1-0.7, y = 0.1) were prepared and studied. X-ray diffraction analysis shows a random distribution of Sr2+ at both the T- and O-sites of spinel lattice. Subsequent oxygen vacancies, empty lattice sites and antisite defects make these materials very promising luminescent materials having variety of optical centres to play with. UV-Vis spectra showed maximum absorption at 220 nm, whereas a broad emission band ranged between 350-550 nm with high intensity peak at 436 nm and two shoulders at 417 and 465 nm is observed when excited at 320 nm. The coordination environment of the optical centres is also affected by the Mn2+/Sr2+ doping resulting in blueshift in the absorbance band. Transition of color from greenish-blue to blue is observed on account of Mn2+ doping in Mg1-xSrxAl2O4 materials.