Synthesis, Structure, and Luminescent Properties of a New Phosphor Y2GaTaO7: Sm3+

Y2GaTaO7 complex oxide and a series of (Y1–xSmx)2GaTaO7 solid solutions were synthesized by the citrate method for the first time. The samples were studied by X-ray diffraction of synchrotron radiation, scanning electron microscopy, diffuse reflection, and photoluminescence. All synthesized compounds have a layered pyrochlore-like structure (space group R 3̄ ). Y2GaTaO7 is a self-activated phosphor that exhibits a wide emission band with a maximum at 455 nm. The origin of the self-luminescence in Y2GaTaO7 is attributed to electron transitions in TaO6 and GaO6 groups. (Y1–xSmx)2GaTaO7 phosphors exhibit bright orange-red radiation under excitation at near-UV light. Their emission spectrum contains bands associated with both the host-luminescence and the f–f-transitions of Sm3+ ions. Concentration quenching of Sm3+ luminescence in (Y1–xSmx)2GaTaO7 is observed at an activator content >7 mol %. Due to the energy transfer from TaO6 and GaO6 to Sm3+ ions, it is possible to change the luminescence spectrum of the phosphor by varying the Sm3+concentration.