Rational synthesis of Eu3+ and Yb3+ single −doped and co-doped Ba0.5Sr0.5TiO3 phosphors for dynamic anti-counterfeiting and fingerprint recognition applications

Abstract

The Eu³⁺ and Yb³⁺ ions single −doped and co-doped Ba_0.5Sr_0.5TiO₃ (BST5) phosphors were prepared by a polyacrylamide gel method. The effects of rare earth ion concentration and ion type on the phase structure, microstructure, optical, color properties and photoluminescence properties of the BST5 phosphor were investigated by various characterization methods. Since the concentration of doped ions is less than 1 %, and Eu³⁺ and Yb³⁺ ions occupy the Ba/Sr site of the BST5 phosphor, the phase structure of the BST5 phosphor is not changed. Microstructure characterization confirmed that the co-doping of Eu³⁺ and Yb³⁺ with BST5 phosphor made the rhomboid particles more uniform in size. In addition to the band absorption of the BST5 phosphor, all phosphors also have two absorption peaks at 371 and 445 nm caused by Eu³⁺ ion ground state ⁷F₀ to excited states ⁵L₆ and ⁵D₂, respectively. Simultaneously, the co-doping changes the lattice constant and crystal structure stability of BST5, resulting in a slight shift in the absorption peak. When the excitation wavelength is 395 nm, BST5:Eu and BST5: 0.25 %Eu:Yb phosphor have the strongest emission peaks at 595 and 598 nm, respectively. The photoluminescence mechanism confirmed that the existence of superexchange between Eu³⁺-O-Ti⁴⁺ and energy transfer between Eu³⁺ and Yb³⁺ enhanced the photoluminescence performance of the BST5:0.25 % Eu:Yb phosphor. The practical application shows that the BST5: Eu/Yb phosphor has a potential application prospect in the field of photoluminescence, dynamic anti-counterfeiting and fingerprint recognition.