Thermally stable Na3.6Y1.8(PO4)3:Eu3+ phosphor, luminescent properties and application in WLEDs

To develop potential phosphors used in ultraviolet (UV) based white light-emitting diodes (WLEDs), a novel red Na3.6Y1.8(PO4)(3):Eu3+ (NYP:Eu3+) phosphor was successfully prepared by a solid-state method. Rietveld refinement analysis determined that NYP has a cubic unit cell with space group Pm-3m. The structural properties were analyzed in detail by employing X-ray diffraction (XRD), transmission electron microscopy (TEM) and energy dispersive spectrometry. Scanning electron microscope (SEM) image revealed the irregular morphology of NYP:Eu-3(+) particles and elemental mapping verified that Eu3+ ions were uniformly distributed on Y3+ sites. Photoluminescence (PL) spectra exhibited strong red emission under the excitation of 394 nm and optimal Eu3+ doping concentration in the NYP host was determined to be 30 mol%. The critical distance was calculated to be about 13.954 angstrom and dipole-dipole interaction was responsible for the concentration quenching mechanism. NYP:Eu3+ phosphor demonstrated high thermal stability with emission intensity at 424 K was 97.4% of that at 298 K. Moreover, by employing the title red, green (Ba,Sr)(2)SiO4:Eu2+, blue BaMgAl10O17:Eu2+ (BAM:Eu2+) phosphors and near UV (NUV) light-emitting diode chip, a WLED device was fabricated, which possessed excellent CIE chromaticity coordinates of (0.3351, 0.3499) and high color rendering index (Ra = 87.5). (C) 2019 Elsevier B.V. All rights reserved.