Luminescence properties of tunable white-light long-lasting phosphor YPO4: Eu3+, Tb3+, Sr2+, Zr4+

Abstract A series of novel YPO 4 : Eu 3+ , Tb 3+ , Sr 2+ , Zr 4+ tunable white-light long lasting phosphors were synthesized by conventional solid-state reaction method. The luminescent properties were systematically characterized by X-ray diffraction, photoluminescent excitation and emission spectra, thermoluminescence spectrum and decay curves. The XRD patterns indicated that the samples belonged to tetragonal phase and co-doping Eu 3+ , Tb 3+ , Sr 2+ and Zr 4+ ions have no effect on the basic crystal structure. Under the excitation of 372 nm wavelength, it was first discovered that the specific concentration of Sr 2+ can improve the emission intensity of Eu 2+ . The blue (Eu 2+ ), green (Tb 3+ ) and red (Eu 3+ ) lights were emitted simultaneously and therefore produced white light in the same YPO 4 matrix. Tunable color from the white to purple region was achieved not only by increasing the concentration of Zr 4+ and Sr 2+ , but also by increasing the concentration of Eu 3+ . The CIE chromaticity coordinates of Y 0.89 PO 4 : Eu 3+ 0.06 , Tb 3+ 0.05 , Sr 2+ 0.06 , Zr 4+ 0.06 (0.33, 0.31) were the closest to point (0.33, 0.33) which delegates the ideal white and trap depths for the two glow peaks are 0.88 eV and 0.85 eV. The fitting decay constant of τ 2 corresponding to the slow exponentially decay components was 101.30 s.