A novel Eu~(3+)-doped ScCaO(BO_3) red phosphor for tricolor-composited high color rendering white light

摘要

Exploration of novel red emitting phosphors containing Eu3+ ions is an everlasting topic in the field of luminescent materials due to the application requirement of warm white light-emitting diodes. In this work, the Eu3+doped ScCaO(BO3) phosphors were synthesized though the high temperature solid-state reaction method. The phase purity and detail information on crystal structure were obtained by X-ray diffraction (XRD) and the technology of Rietveld XRD refinement. Scanning electron microscopy (SEM) was applied to check the particle morphology and EDS mapping was taken to analyze element distributions. Optical properties of the phosphors were studied by measuring the steady-state excitation and emission spectra and also the transient luminescence decays. The emission spectra of ScCaO(BO3):Eu3+ majorly consisted of 5D0-7F1, 7F2 and 7F4 transitions, covering the orange (582-605 nm), red (605-635 nm) and deep red (690-720 nm) spectral regions. The doping concentration of Eu3+ ions was optimized to 12% to maximize the optical performance of the red emitting phosphors, whose CIE coordinate and fluorescent lifetime were (0.6458, 0.3537) and 1.516 ms, respectively. The investigation of the thermal quenching behavior of the ScCaO(BO3):0.12Eu3+ phosphor reveals that the emission intensity of Eu3+ at 400 K can maintain 68.98% of that at room temperature due to the existence of the thermal activation energy of 0.258 eV. Using such a red-emitting material, the prototype warm white LED device with the CIE coordinate of (0.3262, 0.3363), color rendering index of 86.1 and correlated color temperature of 5871 K can be obtained by combining with the blue emitting BaMgAl10O17:Eu2+ and green emitting Zn2SiO4:Mn2+ phosphors and coating all three on a near-UV LED chip. All the results demonstrate that the ScCaO(BO3):0.12Eu3+ phosphor can sever as a potential red emitting candidate for near-UV excited warm WLEDs.