Tunable blue-white-red photoluminescence and long lasting phosphorescence properties of a novel zirconate phosphor: La sub(2)Zr sub(2)O sub(7):Sm super(3+),Ti super(4+)

A novel long lasting phosphorescence phosphor La sub(2)Zr sub(2)O sub(7) :Sm super(3+),Ti super(4+) is firstly synthesized by solid state method at 1673 K in air. The emission spectrum of La sub(2)Zr sub(2)O sub(7) :Sm super(3+),Ti super(4+) consists of a broad band at 460 nm due to charge transfer of O super(2-)_Ti super(4+) and the emission lines of Sm super(3+) in 550-700 nm. By changing the co-doping content of Sm super(3+), the color of photoluminescence and long lasting phosphorescence are tunable and the blue, red even white color can be observed. The spectral overlap reveals the presence of efficient energy transfer between Ti super(4+) and Sm super(3+). The long lasting phosphorescence of the optimal sample can be recorded for about 540s(0.32mcd/m super(2)) and the decay curve can not be exponentially fitted for the presence of two decay origins. It reveals that the Sm super(3+) and Ti super(4+) ions act as not only emission centers but also aliovalent auxiliaries to create proper shallow traps clusters. Additionally, the deep traps (342 K and 411 K) are proved to be stable enough that the La sub(2)Zr sub(2)O sub(7) :Sm super(3+),Ti super(4+) material shows potential applications as not only a long lasting phosphorescence phosphor but also an optical storage material.