Co-Doping Effect on the Optical Properties of Eu(2+/3+) Doped in BaSiO3

To investigate the effect of co-doping on the optical properties of Eu(2+/3+) doped in Ba-0.98SiO3:0.02Eu, the series of Ba-0.96SiO3:0.02Eu, 0.02R(+/3+) (R+ = Li+, K+ or Na+, R3+ = La3+ or Y3+) 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 Eu3+ was thus increased by 3.7 times compared with that of the single-doped Ba-0.98SiO3:0.02Eu(3+). However, the co-doping of R+ does not increase the emission intensity of Eu3+ via the direct F-7(0)-> L-5(6) excitation of Eu3+, but rather decreases it. On the other hand, the emission intensities due to Eu2+ were decreased via the co-doping of R+ but increased via the co-doping of La3+. The present work reveals that the optical properties of Eu3+ or Eu2+ doped in BaSiO3 depend not on the charge state (+ or 3+) of the co-doped ions, but on the co-doped element itself.