Structure and luminescent properties of new Dy3+/Eu3+/Sm3+-activated InNbTiO6 phosphors for white UV-LEDs

A series of novel Dy3+/Eu3+/Sm3+-activated InNbTiO6 phosphors have been prepared by conventional solid state reaction method. Based on the structure refinement, RE3+ ions are preferred to occupy the site of In3+ (2e) in the wolframite-type host lattice. According to their UV-visible diffusion reflectance spectra, the band gap and absorption property of un-doped InNbTiO6 sample can be tuned by the dopants. Under UV-visible light excitation, Dy3+/Eu3+/Sm3+ activators in this matrix mainly show emission lines originating from their characteristic f -> f transitions. The optimal excitation and emission wavelength are 385 nm and 581 nm for Dy3+, 394 nm and 616 nm for Eu3+, 406 nm and 615 nm for Sm3+. Concentration quenching occurs at 0.06 for Dy3+, 0.06 for Eu3+, and 0.04 for Sm3+, ascribed to resonant q-q, q-q, and d-q interactions, respectively. The luminescence lifetimes are determined to be 0.13, 0.50, and 0.50 ms for InNbTiO6:0.06Dy(3+), InNbTiO6:0.06Eu(3+), and InNbTiO6:0.04Sm(3+), respectively. The Dy3+, Eu3+, and Sm3+ doped phosphors exhibited yellowish-white, red, and orange-red luminescence, respectively. The quantum yields and thermal stability of representative phosphors have been investigated. Present work shows that these new phosphors are promising for application in UVLED solid-state lighting devices.