Dysprosium doped novel apatite-type white-emitting phosphor Ca9La(PO4)5(GeO4)F2 with satisfactory thermal properties for n-UV w-LEDs

A novel apatite structure phosphor Ca9La(PO4)(5)(GeO4)F-2:Dy3+ (CLPGF:Dy3+) with a hexagonal lattice in the P6(3)/m space group was synthesized via a facile solid state technique. The crystal and fine local structure as well as their photoluminescence properties were investigated in detail. The CLPGF:Dy3+ phosphor can absorb in the UV-vis spectral region of 290-475 nm and exhibit two intense emission bands centered at 485 and 580 nm, which ascribes to F-4(9/2) -> H-6(15/2) and F-4(9/2) -> H-6(13/2) transitions of Dy3+, respectively. The concentration quenching of Dy3+ emission occurs via the energy transfer among the nearest-neighbor ions and the corresponding quenching mechanism was verified to be the dipole dipole interaction. The quantum efficiencies of the phosphors were examined to be 72.9% and its luminescence intensity at 150 degrees C decreases to 93.8% and 98.6% of the initial value at room temperature, which corresponds to F-4(9/2) to H-6(15/2) transition and F-4(9/2) to H-6(13/2) transition of Dy3+ ions, respectively.Their interesting photoluminescence properties indicate that the CLPGF:Dy3+ phosphor is a promising white-emitting candidate for w-LEDs applications. (C) 2016 Elsevier Ltd. All rights reserved.