Effects of Bi3+ doping on the optical properties of Er3+:Y2O3

The influences of Bi3+ doping on the optical properties of Er3+:Y2O3 are investigated under UV and IR excitations. The emission intensity of Er3+ is remarkably enhanced by the introduction of Bi3+ under both two excitations. The emission enhancement under UV excitation originates from the energy transfer from Bi3+ to Er3+, while under IR excitation it can be attributed to the modification of the local crystal field around the Er3+.

Research highlights▶ As the emission of most luminescent materials does not have enough intensity, it is still a formidable challenge about how to improve the emission efficiency of these materials. It is known that doping of sensitizer ions or break of the crystal field symmetry can lead to the increase in emission intensity of rare-earth ions. The emission band of Bi3+ overlaps with the 4I15/2 → 2H11/2, 4S3/2 transition of Er3+, so Bi3+ can also be used as a sensitizer of Er3+ for radiative energy transfer process. The broad absorption band of Bi3+ is beneficial to absorb more energy and enhance Er3+ emission under UV excitation. Moreover, as the radius of Bi3+ is lager than that of Y3+, substituting Y3+ with Bi3+ can modify the symmetry of crystal field in Y2O3 which is in favor of the enhancement of emission intensity. In this study, Bi3+ is selected as codopant to improve the luminescent efficiency of Er3+. The emission intensity of Er3+ is improved both under 330 nm and 980 nm excitations. The mechanisms of the phenomena are discussed in detail.