Structural and optical properties of highly thermally active Gd₂Zr₂O₇:Dy³⁺ phosphors for lighting applications

Near white light emitting (Gd_2−2x Dy_2x Zr₂O₇) (2x = 0.01, 0.02, 0.04, 0.06, 0.08) phosphors have been synthesized by the facile hydrothermal method. To examine the structural and optical properties, the prepared phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence spectroscopy (PL) and UV–Vis diffuse reflectance spectroscopy. The XRD results confirm the defect fluorite structure of the prepared phosphors having cubic crystal system with space group Fm3m and incorporation of Dy³⁺ ions does not modify host lattice crystal structure. The photoluminescence properties have been well studied in respect of excitation spectra, emission spectra and decay kinetics. The PL emission spectra of the sample under 351 nm UV excitation exhibits two intense peaks around 484 nm and 580 nm which are attributed to the transitions ⁴F_9/2–⁶H_15/2 and ⁴F_9/2–⁶H_13/2, respectively of Dy³⁺ ion. The emission intensity goes on increasing until Dy³⁺ doping concentration reaches at 2 mol% and intensity decreases thereafter on higher concentration. The average life times are found to decrease with the increase of Dy³⁺ concentration. Photometric studies such as CIE color coordinate, CCT and Color purity facilitate that the reported phosphors can generate near white light emission. Temperature dependent PL spectral measurement reveals that the emission intensity as well as the life time gradually increases with temperature. Thus, the affirmative experimental result indicates that the Dy³⁺ ions doped Gd₂Zr₂O₇ phosphors can be used as active near white lighting emitting phosphor materials.