Photoluminescence of Tb3+ and Mn2+ activated Ca8MgGd(PO4)7 under vacuum ultraviolet excitation

Novel Tb3+ and Mn2+ activated Ca8MgGd(PO4)(7) phosphors were synthesized by solid-state reaction and their photoluminescence properties in vacuum ultraviolet region were investigated for the first time. It can be observed from the excitation spectra that the host-related absorption band is located around 170 nm, and it overlaps the O2- -> Tb3+ charge transfer band of Ca8MgGd(PO4)(7):Tb3+ around 161 nm and the (3)d(5) -> 3d(4)4s transition band of Ca8MgGd(PO4)(7):Mn2+ near 200 nm. The 4f-4f 5d spin-allowed and spin-forbidden transitions of Tb3+ are verified to be located at 170-250 and 257-271 nm, respectively. Upon 147 nm excitation, the dominant emission peak intensity of the Ca8MgGd0.1(PO4)(7):0.9Tb(3+) phosphor is about 2.7 times stronger than that of the commercial Zn2SiO4:Mn2+ green phosphor, and the brightness of the former with a short decay time of 2.5 ms is about 98% of the latter's. The Ca8MgGd(PO4):Mn2+ phosphor excited at 147 nm exhibits a deep red emission around 650 nm, which could be attributed to the T-4(1) -> (6)A(1) transition of Mn2+, with the CIE index (0.679, 0.321). In a word, the results above indicate that both Tb3+ and Mn2+ activated Ca8MgGd(PO4)(7) phosphors could be promising for PDP or Hg-free lamp applications. (C) 2011 Elsevier B.V. All rights reserved.