Tunable luminescence of Eu3+/Tb3+-doped MgZrO3: from single doping to co-doping for anti-counterfeiting applications.

MgZrO3 (MZO) has been extensively investigated for its electrical, structural, optical and catalytic properties in environmental applications. However, the fabrication of color-tunable MZO:0.10Tb3+, zEu3+ [z = 0.005, 0.010, 0.030, 0.050, and 0.070] nanophosphors and their potential applications in anti-counterfeiting inks have not yet been reported. In this work, red-emitting MZO:xEu3+, green-emitting MZO:yTb3+ nanophosphors, and color-adjustable MZO:0.10Tb3+, zEu3+ nanophosphors were successfully synthesized using a sol-gel combustion approach. The prepared samples exhibited a highly crystalline structure with a nano cube morphology. The optical band gap gradually decreased with increasing dopant and co-dopant concentrations. Urbach energy analysis indicated a higher degree of structural disorder in the doped samples, particularly in the MZO:yTb3+ and co-doped MZO:0.10Tb3+, zEu3+ compositions. The incorporation of Eu3+ and Tb3+ ions into the MZO host lattice enabled precise control over the luminescence behavior, allowing systematic tuning of the emission color by adjusting the relative dopant ratios. Under excitation at 280 nm, the co-doped MZO:0.10Tb3+, zEu3+ nanophosphors exhibited an emission that shifted from the green to the red region through the yellow region, accompanied by long luminescence lifetimes. Furthermore, these co-doped nanophosphors were successfully employed in the formulation of luminescent inks for anti-counterfeiting applications.