Luminescence investigation of lanthanum ions (Eu3- or Tb3+) doped SrLaGa3O7 fluorescent powders

SrLaGa3O7:Eu3+ and SrLaGa3O7:Tb3+ fluorescent powders were synthesized using solid sintering procedure. The crystal structure and luminescence of the synthesized fluorescent powders were surveyed. XRD patterns of the synthesized fluorescent powders demonstrate that they have the single tetragonal phase. Under excitation at 392 nm, SrLaGa3O7:Eu3+ fluorescent powders exhibit photoluminescence bands rooting in D-5(0) -> F-7(0), 1, 2, 3, 4 transitions of Eu3+. In SrLaGa3O7, La3+ ions are surrounded octahedrally by eight ions and there is only one mirror plane paralleling to c axis in these distorted octahedrons. This characteristic induces the existence of photoluminescence band resulting from D-5(0) -> F-7(0) transition and the strongest photoluminescence band resulting from D-5(0) -> F-7(2) transition. Under excitation at 265 nm, SrLaGa3O7:Tb3+ fluorescent powders show photoluminescence bands resulting from D-5(3) -> F-7(3) and D-5(4) -> F-7(6), 5, 4, 3 transitions of Tb3+. The band resulting from D-5(4) -> F-7(5) transition is strongest because that this transition has the largest probability for both electric-dipole and magnetic-dipole transitions. The decay curves of SrLaGa3O7:Eu3+ and SrLaGa3O7:Tb3+ fluorescent powders show a single exponential characteristic.