Novel red-emitting Mn⁴⁺ activated Mg₄Ta₂O₉ phosphors for flexible display and anti-counterfeiting applications

In this report, a series of rare-earth-free Mg₄Ta₂O₉: Mn⁴⁺ phosphors were obtained by a solid-state reaction technique. The optimal doping content of Mn⁴⁺ ions in the Mg₄Ta₂O₉ lattice was determined as 0.02 mol. The physical properties of the prepared Mg₄Ta₂O₉: Mn⁴⁺ phosphors, including the crystal structure, elemental composition, morphology, and microstructure, were studied. Their photoluminescence performance and temperature stability were carefully investigated. The excitation wavelength of the Mg₄Ta₂O₉: Mn⁴⁺ phosphor was found to be 269 nm. Under this excitation, the Mg₄Ta₂O₉: 0.02Mn⁴⁺ phosphor emitted red emission with the Commission Internationale de l'Eclairage chromaticity coordinate (0.7008, 0.2991). When the temperature increased, the as-prepared Mg₄Ta₂O₉: 0.02Mn⁴⁺ phosphor retained 77.4 % and 69.3 % of its initial photoluminescence emission intensity (at 303 K) at 423 and 483 K, respectively. Moreover, a flexible Mg₄Ta₂O₉: 0.02Mn⁴⁺-polydimethylsiloxane film was fabricated, which resulted in a red emission under ultraviolet-C irradiation. Thus, the phosphors have promising potential for high-stability, flexible, and solid-state optical display applications.