Synthesis of several enhanced ions doped yttrium&gadolinium oxide red phosphors by a polyethyleneglycol-assisted co-precipitation solution method

The red-emitting (Y_{0.92−x−y−z},Gd_x)₂O₃:Eu³⁺,yBi³⁺,zLi⁺ phosphors have been synthesized via a polyethyleneglycol (PEG)-assisted co-precipitation solution method. The X-ray diffraction (XRD) patterns showed that the obtained samples crystallized in a cubic crystal system with space group I_a3(206) (a = 1.0604 nm) and Eu³⁺, Gd³⁺, Bi³⁺,Li⁺ ions could be well doped into the substrate. It is shown in the scanning electron microscopy (SEM) images that the particles with approximately spherical or regular small block in morphology, the average crystallite size was calculated to be 300–500 nm and the PEG-assisted sample showed better dispersancy. The photoluminescence spectra and fluorescence decay curves indicated that the phosphors could be excited by 254 and 395 nm, the emission intensity and color purity could be improved with the doping of moderate Gd³⁺, Bi³⁺ and Li⁺ and the lifetime decreased a lot with the co-doping of Gd³⁺ and Bi³⁺, which may expand the application of the phosphors. The optimal addition concentrations of Gd³⁺, Bi³⁺, Li⁺ were 20, 2 and 5 mol%. Furthermore, the action mechanism of PEG and luminous property enhancement mechanism of Gd³⁺, Bi³⁺ and Li⁺ were discussed in the present work.