Tunable emission, energy transfer and charge compensation in SrMoO4:Sm3+,Tb3+,Na+ phosphor

A series of SrMoO4:Sm(3+),Tb(3+),Na(+) phosphors was synthesized using a high-temperature solid-state reaction method in air. On excitation at 290 nm, SrMoO4:Sm(3+),Tb(3+) phosphor emitted light that varied systematically from green to reddish-orange on changing the Sm(3+) and Tb(3+) ion concentrations. The emission intensities of SrMoO4:Sm(3+) and SrMoO4:Sm(3+),Tb(3+) phosphors were increased two to four times due to charge compensation when Na(+) was added as a charge compensator. The luminescence mechanism and energy transfer could be explained using energy-level diagrams of the MoO4(2-) group, Sm(3+) and Tb(3+) ions. SrMoO4:Sm(3+),Tb(3+),Na(+) could be used as reddish-orange phosphor in white light-emitting diodes (LEDs) based on an ~ 405 nm near-UV LED chip. This research is helpful in adjusting and improving the luminescence properties of other phosphors.