Extending the luminescence properties of zinc gallogermanate via co-doping with cost-effective metals ions (Cr3+/Mg2+, Cr3+/Ca2+, and Cr3+/Sr2+)

The huge applications of red-light-emitting materials paying the research attention to reduce the cost of production and raw materials. Therefore, abundant cations of alkaline-earth metals, e.g., Mg2+, Ca2+, and Sr2+ were successfully incorporated with Cr3+: Zn3Ga2Ge2O10 (Cr-ZGGO) as co-activators via simple solid-state method. The X-ray diffraction results of all samples confirmed the formation of zinc gallogermanate superstructure with two cubic phases ZnGa2O4 and Zn2GeO4. The particle imaging of Cr-ZGGO and Ca@Cr-ZGGO via field emission scanning electron microscopy reveals a significant change in morphology and particle size by Ca2+ co-doping. Meanwhile, the energy dispersive X-ray spectroscopic analysis and mapping techniques elucidate the exact chemical composition of the calculated stoichiometric substitution and illustrate the equal distribution of all elements over the whole sample. Optical bandgap energy of Mg2+, Ca2+, and Sr2+ co-doped phosphors are lower than Cr-ZGGO. The Sr@Cr-ZGGO displays the most intense photoluminescence peak and the broadest emission in the near-infrared region as a result of increasing light traps and generation of new paths between the energy levels of trapping centers.