Tunable multicolor luminescence and energy transfer mechanism in Eu3+/Dy3+ co-doped Ca2Sb2O7 phosphor under UV excitation

• Novel single-phase Ca 2 Sb 2 O 7 :xEu 3+ ,yDy 3+ phosphors with tunable multicolor emission under ultraviolet (UV) excitation were synthesized. • The photoluminescence spectra exhibit characteristic emission bands of both Dy 3+ and Eu 3+ ions along with an intense blue emission band of host. • Efficient energy transfer occurs from host to Dy 3+ /Eu 3+ ions and also from Dy 3+ to Eu 3+ . • Energy transfer mechanism is investigated in detail using decay curves and Dexter’s theory. • Emission color can be tuned from blue to red by properly modulating the concentration of Dy 3+ /Eu 3+ , making it a potential candidate for multicolor displays and WLEDs. A series of Ca (2-x-y) Sb 2 O 7 :xDy 3+ ,yEu 3+ phosphors with tunable multicolor luminescence were synthesized via solid-state reaction method. The XRD, EDX and HR-TEM analysis confirmed the phase purity and the crystallinity of the samples. Under ultraviolet (UV) excitation, Ca (2-x-y) Sb 2 O 7 :xDy 3+ ,yEu 3+ phosphors exhibit characteristic emission bands of both Dy 3+ and Eu 3+ ions, along with an intense blue emission band of the host. The emission peaks at 575 and 660 nm correspond to 4 F 9/2 → 6 H 13/2 and 4 F 9/2 → 6 H 11/2 transitions of Dy 3+ ions, and the peaks at 528 and 612 nm originate from 5 D 1 → 7 F 1 and 5 D 0 → 7 F 2 transitions of Eu 3+ ions, respectively. There exists efficient energy (ET) transfer from host to Eu 3+ /Dy 3+ ions, as well as from Dy 3+ to Eu 3+ ions. The decay lifetime of host and Eu 3+ /Dy 3+ emissions were calculated to be in the microsecond range. By properly modulating the concentration of Eu 3+ /Dy 3+ ions, the CIE chromaticity coordinates of the samples vary from (0.144, 0.097) to (0.446, 0.312). Hence, multicolor emission which can be tuned from blue to bluish-white and eventually to reddish-white can be obtained in the warm CCT region. The results indicate that Ca 2 Sb 2 O 7 :Dy 3+ ,Eu 3+ phosphor could be a promising candidate for UV excited WLEDs and multicolor displays.