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

Abstract

Near white light emitting (Gd2−2x Dy2x 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 4F9/2–6H15/2 and 4F9/2–6H13/2, 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.