Physical and optical studies of Gd O S:Eu nanophosphors by microwave irradiation and γ-irradiation methods.

Gd O S:Eu 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 Gd O S:Eu 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 D → F transition of Eu ions. However, Gd O S:Eu nanophosphors following microwave treatment showed better luminescence intensity than Gd O S:Eu nanophosphors treated with γ-irradiation. This difference was attributed to the crystallinity phase and surface quenching effects of Gd O S:Eu nanophosphors. The reaction mechanisms of Gd O S:Eu nanophosphors in both methods are discussed in detail.