Columnar Gd2O3:Eu3+/Tb3+ phosphors: preparation, luminescence properties and growth mechanism
Columnar Gd2O3:Eu3+/Tb3+ phosphors were successfully prepared by a solvothermal method and subsequent calcination process. The structure, morphology and luminescence properties of the as-prepared products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectra. The XRD results indicate that the precursor sample is hexagonal Gd(OH)3 while the calcinated sample is cubic Gd2O3. SEM and TEM images show that both the precursor and the calcined samples are columnar, with lengths of 220 nm and 214 nm and diameters of 130 nm and 126 nm, respectively. The fluorescence spectrum shows that Gd2O3:Eu3+ generates a characteristic red emission when stimulated by ultraviolet light with a wavelength of 250 nm, which corresponds to the 5D0 → 7F2 transition of Eu3+. Gd2O3:Tb3+ generates a characteristic green emission when stimulated by ultraviolet light with a wavelength of 240 nm, which corresponds to the 5D4 → 7F5 transition of Tb3+.