Synthesis and characterization of Ca3Lu(GaO)3(BO3)4:Ce3+,Tb3+ phosphors: tunable-color emissions, energy transfer, and thermal stability

Blue-green dual-emitting phosphors Ca3Lu(GaO)(3)(BO3)(4):Ce3+,Tb3+ (CLGB:Ce3+,Tb3+) were synthesized via a traditional solid-state reaction method. The phase of the phosphors was characterized by X-ray diffraction and the luminescence properties were investigated using the excitation and emission spectra, decay curves, temperature-dependent emission spectra, CIE chromaticity coordinates, and the internal quantum efficiency. Under 345 nm UV light excitation, Ce3+ singly doped CLGB phosphors presented intense blue light in the 350-550 nm wavelength region with a maximum peak at 400 nm. In sharp contrast, CLGB:Ce3+,Tb3+ phosphors showed both the blue and green emission wavelengths of Ce3+ and Tb3+ ions, respectively. The overall emission colors can be tuned from blue (0.164, 0.042) to green (0.331, 0.485) via increasing the concentration of Tb3+ ions, due to the energy transfer (ET) from Ce3+ ions to Tb3+ ions. The optimal doping concentration of Tb3+ ions in CLGB:Ce3+,Tb3+ phosphors was found to be 40 mol%. The mechanism of the ET from the Ce3+ to Tb3+ ions was demonstrated to be electric quadrupole-quadrupole interaction. The CLGB:0.04Ce(3+),0.40Tb(3+) sample possessed a high IQE of 54.2% and excellent thermal stability with an activation energy of 0.3142 eV when excited at 345 nm. The integrated emission intensity of CLGB:0.04Ce(3+),0.40Tb(3+) at 423 K was found to be about 74% of that at 303 K. Finally, under 300 mA driven current, the fabricated prototype white light-emitting diode showed CIE chromaticity coordinates of (0.3996, 0.3856) and high color rending index of 81.2. Considering all the above characteristics, the obtained CLGB:Ce3+,Tb3+ phosphors can be a type of multicolor emitting phosphor for application in white light-emitting diodes.