Studies on the luminescence properties of europium doped strontium alumino-silicate phosphors by solid state reaction method

摘要

The Sr_2Al_2SiO_7:Eu~(2+) and Sr_2Al_2SiO_7:Eu~(3+) phosphors were prepared by the traditional high temperature solid state reaction method. The crystal structures of sintered phosphors were gehlenite type structure which belongs to the tetragonal crystallography with space group P42_1m. Thermoluminescence properties of these phosphors were investigated and results were also compared. Under the ultra-violet excitation (345 nm), the Sr_2Al_2SiO_7:Eu~(2+) phosphor would emit bluish-green (cyan) light, belonging to the broad emission band ascribed to the 4f~65d~1 → 4f~7 transition. The emission spectrum (λ_(ex) = 395 nm) of Sr_2 Al_2SiO_7:Eu~(3+) phosphor were consisted of two emission peaks at 593 and 613 nm, which were attributed to ~5D_0 →• ~7F_1 and ~5D_0 → ~7F_2 of Eu~(3+) ions. The strongest excited band at 395 nm can be assigned to ~7F_0 → ~5L_6 transition of Eu~(3+) ions due to the typical f-f transitions within Eu~(3+) of 4f~6 configuration. Commission International de I'Eclairage color coordinates of Sr_2Al_2SiO_7:Eu~(2+) and Sr_2Al_2SiO_7:Eu~(3+) phosphors were suitable as bluish-green and orange-red light emitting phosphors respectively. The mechanoluminescence (ML) intensity of Sr_2Al_2SiO_7:Eu~(2+) and Sr_2Al_2SiO_7:Eu~(3+) phosphors increase linearly with increasing impact velocity of the moving piston. Thus the present investigation indicates that the piezo-electrically induced de-trapping model is responsible to produce ML in sintered phosphors.