Co-Doping Effect on the Optical Properties of Eu((2+/3+)) Doped in BaSiO(3)

To investigate the effect of co-doping on the optical properties of Eu((2+/3+)) doped in Ba(0).(98)SiO(3):0.02Eu, the series of Ba(0).(96)SiO(3):0.02Eu, 0.02R(+/3+) (R(+) = Li(+), K(+) or Na(+), R(3+) = La(3+) or Y(3+)) phosphors were synthesized using a solid-state reaction method. The excitation efficiency due to the charge transfer band (CTB) was enhanced via co-doping of R(+) and the emission intensity due to Eu(3+) was thus increased by 3.7 times compared with that of the single-doped Ba(0).(98)SiO(3):0.02Eu(3+). However, the co-doping of R(+) does not increase the emission intensity of Eu(3+) via the direct (7)F(0)→(5)L(6) excitation of Eu(3+), but rather decreases it. On the other hand, the emission intensities due to Eu(2+) were decreased via the co-doping of R(+) but increased via the co-doping of La(3+). The present work reveals that the optical properties of Eu(3+) or Eu(2+) doped in BaSiO(3) depend not on the charge state (+ or 3+) of the co-doped ions, but on the co-doped element itself.