Luminescent properties of Eu³⁺-doped BaLn₂ZnO ₅ (Ln=La, Gd, and Y) phosphors by the sol-gel method

Three series of Eu³⁺-doped BaLn_2-xEu _xZnO₅ (Ln=Y, Gd, and La) phosphor powders were prepared by the sol-gel process. Parameters that affect the photoluminescence (PL) intensity of phosphors were investigated in detail. The phase formation and identification of samples were characterized by thermogravimetry and differential thermal analysis and X-ray diffraction (XRD), respectively. The morphologies of the phosphor particles and the spectra of the as-prepared phosphors were investigated by means of field-emission scanning electron microscopy (FE-SEM) and PL measurements. The XRD results reveal that the sample adopts a tetragonal structure for BaLa_2-xEu_xZnO ₅ and the other two samples adopt an orthorhombic structure in our experimental ranges, and the formation temperature of the pure phase increases with the decreasing of the radius of Ln³⁺ ions. The FE-SEM images indicate that the size and the shape of phosphor particles are regular. The PL spectra of phosphors BaLn_2-xEu_xZnO₅ (Ln=Y, Gd, and La) show the characteristic emissions of Eu³⁺. And the emission color of phosphors BaLn_2-xEu_xZnO₅ (Ln=Y, Gd) could be tuned from white to red by changing the concentration of Eu ³⁺, but the BaLa_2-xEu_xZnO₅ only shows red emission and was independent to the concentration of Eu³⁺.