Long lasting phosphorescence of Gd2O2S:Eu,Ti,Mg nanorods via a hydrothermal routine

This paper reports a novel hydrothermal method to synthesize nanorod like Gd2O2S:Eu,Ti,Mg persistent phosphor and the characterization of the same. Hydrothermally prepared Gd(OH)3 nanorod precursor, codoped with Eu, Ti and Mg, was converted into the aimed phosphor by calcinating the precursor in CS2 atmosphere. XRD investigation revealed a pure phase of Gd2O2S, indicating that the codoped ions, Eu, Ti and Mg, occupy the lattice position within Gd2O2S crystal, rather than form secondary phase in the obtained phosphor powder. SEM observation showed that the phosphor calcined in CS2 atmosphere inherited the rod-like shape from the precursor, indicating the advantage of the CS2 routine in controlling the phosphor morphology. HRTEM investigation further revealed a crystalline nature of the nanorods, as well as a preferred growth along c axis. When the nanorods were exposed to UV illumination, bright orange emission was generated, due to the intrinsic transitions of Eu3+. The Eu3+ concentration and the calcination temperature were two key factors that greatly influent the photo luminescent behavior of the prepared Gd2O2S:Eu,Ti,Mg phosphor. Persistent luminescence was readily observed after the UV source was switched off, due to the formation of electron traps with suitable trap depth within the matrix by the codoped Ti4+ and Mg2+ ions.