Tunable luminescence properties of NaLa(MoO4)2:Ce3+,Tb3+ phosphors for near UV-excited white light-emitting-diodes

The NaLa(MoO4)(2):Ce3+,Tb3+ phosphors were synthesized by a high temperature solid-state reaction. Codoping of Ce3+ enhances the emission intensity of Tb3+ greatly by transferring its excitation energy to Tb3+. Through an efficient energy transfer process, the obtained phosphors exhibit both a indigo emission of Ce3+ and a yellowish green emission of Tb3+ with considerable intensity under near-ultraviolet excitation (339 nm). The energy transfer mechanism from Ce3+ to Tb3+ in NaLa(MoO4)(2) host was demonstrated to be dipole-quadrupole interaction. The varied emitted color of the phosphors from indigo to yellow-greenish can be achieved by properly tuning the relative ratio of Ce3+ and Tb3+ through the energy transfer from the Ce3+ to Tb3+ ions. These results indicate that the NaLa(MoO4)(2):Ce3+,Tb3+ phosphors have potential applications as an UV-convertible phosphor for white light emitting diodes because of its effective excitation in the near ultraviolet range. (C) 2011 Elsevier B.V. All rights reserved.