UV emissions in Gd3Â + doped or Gd3Â +-Pr3Â + Co-doped III-III perovskite-type RMO3 (RÂ =Â Y, La; MÂ =Â Al, Ga)

The effects of Gd3 +-Pr3 + co-doping on the Gd3 + UV emission properties were investigated using Gd3 + doped and Gd3 +-Pr3 + co-doped III-III perovskite-type oxides (YAlO3, LaAlO3, and LaGaO3). All the samples had a narrow UV emission at 314 nm. Pr3 + co-doping in the YAlO3 host enhanced the UV emission from Gd3 +, but the other hosts, LaAlO3 and LaGaO3, did not. In Gd3 +-Pr3 + co-doped YAlO3, the Pr 5d state, which appeared in the band gap and did not overlap the conduction band, provided an intense absorption due to the Pr3 + 4f-5d transition, which enhanced the Gd3 + emission intensity by transferring the excitation energy absorbed by the Pr3 + ions to Gd3 +. On the other hand, in Gd3 +-Pr3 + co-doped LaAlO3 and LaGaO3, the Pr 5d state partly or completely overlapped the conduction band. Although the excitation energy was absorbed by Pr3 +, the energy was transferred to the host lattice through the conduction band. These results suggest that the energy location of the Pr 5d state relative to the conduction band substantially influences the energy transfer from Pr3 + to Gd3 +.