Single phase GdPO4: Dy3+ microspheres blue, yellow and white light emitting phosphor

Abstract

Luminescent microspheres, Gd(1−x)DyxPO4 have been synthesized using simple combustion method for the first time. SEM images show that the obtained powders are formed by dispersed microscaled spheres with diameter ranging from 0.5 to 1 μm. The X-ray diffraction, FTIR and Raman spectroscopy studies reveal that the microparticles annealed at 800 °C crystallized in a monoclinic phase with space group P21/n. Under host Gd3+ sensitization, Gd(1−x)DyxPO4 emission spectra of Dy3+ show a broad blue band attributed to transitions 4I15/2 + 4I13/2 + 4I11/2 + 4F9/2 → 6H15/2, a sharp yellow band due to 4F9/2 → 6H13/2 transition, and the little red band of 4F9/2 → 6H11/2 transition. Blue and white emissions have been obtained at low and high Dy3+ concentration, respectively due the energy transfer from Gd3+ to Dy3+. Under direct 4f–4f excitation of Dy3+ in GdDPO4, three bands attributed to 4F9/2 → 6H15/2, 6H13/2, 6H11/2 transitions have been observed resulting in a yellow light emission. The emission bands intensity are discussed as function of GdPO4 structure. They are in well agreement with crystal structure of the host lattice GdPO4 in contrast to reported works. The decay rates for the 4F9/2 level are found to be deviated from exponential to non-exponential nature with increase of Dy3+ concentration. A promising white-light emission for white LED operating under UV excitation is investigated from single-phased phosphor. The obtained results suggest a potential application of GdPO4:Dy3+ microspheres as alternatives to replace bulk materials for many application fields, including light display systems and optoelectronic devices.