Physical and optical studies of Gd2 O2 S:Eu3+ nanophosphors by microwave irradiation and γ-irradiation methods.

Gd2 O2 S:Eu3+ nanophosphors have been successfully synthesized using microwave irradiation and γ-irradiation methods with polyvinyl pyrrolidone as a stabilizer. The physical and luminescence spectra were compared. The morphologies of both Gd2 O2 S:Eu3+ nanophosphors were in the hexagonal phase and mainly consisted of spherical nanostructures with diameters of ~90 nm and ~50 nm for both microwave irradiation and γ-irradiation methods. Upon 325 nm of ultraviolet (UV) light excitation, strong red emissions (626 nm) were observed for both methods; these emissions corresponded to the 5 D0 →7 F2 transition of Eu3+ ions. However, Gd2 O2 S:Eu3+ nanophosphors following microwave treatment showed better luminescence intensity than Gd2 O2 S:Eu3+ nanophosphors treated with γ-irradiation. This difference was attributed to the crystallinity phase and surface quenching effects of Gd2 O2 S:Eu3+ nanophosphors. The reaction mechanisms of Gd2 O2 S:Eu3+ nanophosphors in both methods are discussed in detail.