Luminescence properties of high thermal stability Sr2ScTaO6:Ln3+ (Ln3+ = Sm3+/Dy3+) phosphors with novel double perovskite structures

A series of single-phase Sr2ScTaO6:Ln3+ (Ln3+ = Sm3+/Dy3+) phosphors were successfully prepared by the traditional high-temperature solid-state method, and the effects of different Ln3+ doping concentrations on the luminescence properties of the phosphors were studied. The structure and luminescence properties of the phosphors were characterized by powder X-ray diffraction (XRD), photoluminescence, fluorescence lifetime and thermal stability. Under the excitation of 405 nm, the Sr2ScTaO6:Sm3+ samples have three emission peaks, corresponding to the 4G5/2→6HJ/2 (J = 5, 7, and 9) transitions of Sm3+. The Sr2ScTaO6:Dy3+ samples have two main emission peaks at 493 nm (4F9/2→6H15/2) and 581 nm (4F9/2→6H13/2) for 366 nm excitation. Due to the different energy transfer between different energy levels, the decay time of Sm3+ and Dy3+ ions are different. The phosphors show excellent thermal stability, and the emission intensity are 85 % and 80 % for Sm3+ and Dy3+ ions at 423 K, respectively. These results demonstrate that the Sr2ScTaO6:Ln3+ (Ln3+ = Sm3+/Dy3+) phosphors have great potential as a single-phase luminescence materials for near-ultraviolet (n-UV) excitation.