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

摘要

The Eu3+-activated K2Gd(WO4)(PO4) 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 Eu3+ ions corresponding to the D-5(0) -> F-7(1,2,3,4) transitions. Both the PL spectra and decay curves suggested that there is no concentration quenching in the Eu3+-activated K2Gd(WO4)(PO4) red-emitting phosphors. Moreover, the K2Gd(WO4)(PO4):Eu3+ 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 K2Gd(WO4)(PO4):Eu3+ 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 Eu3+ ions in the K2Gd(WO4)(PO4) host lattice, a theoretical calculation based on the Judd-Ofelt theory was performed and optical transition parameters of Omega(2) and Omega(4) were found to be 2.67x10(-20) and 1.29x10(-20) cm(2), respectively. These outstanding characteristics indicated that the Eu3+-activated K2Gd(WO4) (PO4) red-emitting phosphors may have potential applications in solid-state lighting.