Highly efficient Eu3+-activated K2Gd(WO4)(PO4) red-emitting phosphors with superior thermal stability for solid-state lighting

Abstract

Abstract The Eu 3+ -activated K 2 Gd(WO 4 )(PO 4 ) red-emitting phosphors were successfully synthesized by means of solid-state reaction route. The X-ray diffraction, field-emission scanning electron microscope, photoluminescence (PL) spectra and decay curves were employed to characterize these phosphor samples. Under 396 nm excitation, these samples exhibited bright red emissions of Eu 3+ ions corresponding to the 5 D 0 → 7 F 1,2,3,4 transitions. Both the PL spectra and decay curves suggested that there is no concentration quenching in the Eu 3+ -activated K 2 Gd(WO 4 )(PO 4 ) red-emitting phosphors. Moreover, the K 2 Gd(WO 4 )(PO 4 ):Eu 3+ phosphors also exhibited good color coordinates, high color purity (93.1%) as well as high quantum efficiency (64.7%). Furthermore, the temperature-dependent PL spectra revealed that K 2 Gd(WO 4 )(PO 4 ):Eu 3+ phosphors had superior thermal stability and the activation energy was determined to be 0.19 eV. Additionally, in order to study the local crystal environment of the Eu 3+ ions in the K 2 Gd(WO 4 )(PO 4 ) host lattice, a theoretical calculation based on the Judd-Ofelt theory was performed and optical transition parameters of Ω 2 and Ω 4 were found to be 2.67×10 –20 and 1.29×10 –20 cm 2 , respectively. These outstanding characteristics indicated that the Eu 3+ -activated K 2 Gd(WO 4 )(PO 4 ) red-emitting phosphors may have potential applications in solid-state lighting.