Three distinct Sm2+ impurity centers, a single Sm3+ impurity center, and a color center were identified in KY3F10 with 1 mol.% of Sm ion dopant by their emission and excitation spectra in the vacuum ultraviolet (VUV), ultraviolet (UV), and visible regions. The excited states of the Sm2+ centers consisted of the lower 5 DJ (J = 0,1,2,3) multiplets and the higher lying 4f(5)5d excited states. VUV or UV excitation directly into the 4f(6) -> 4f55d transitions of Sm2+ produced cascade emission from the metastable D-5(J) (J = 3,2,1,0) multiplets to the lowest F-7(J) (J = 0,1,2,3,4) multiplets at low temperatures. Energy transfer from Sm2+ to Sm3+ ions was observed in the excitation spectra of the Sm3+ emission. Excitation at 532 nm for a sample temperature of 300 K produced a broad emission band with a peak at 660 nm and sharp emission lines at 680, 692 and 738 nm, being due to Sm2+. 532 nm irradiation for 30 minutes decreased the intensity of the broadband to one-quarter of the initial intensity and increased slightly the intensities of the sharp lines.

Keywords: Phosphor; Samarium ions; Energy transfer; Dynamics of the excited states; KY3F10