Synthesis and characterization of Ca 3 Lu(GaO) 3 (BO 3 ) 4 :Ce 3+ ,Tb 3+ phosphors: tunable-color emissions, energy transfer, and thermal stability.

Blue-green dual-emitting phosphors Ca 3 Lu(GaO) 3 (BO 3 ) 4 :Ce 3+ ,Tb 3+ (CLGB:Ce 3+ ,Tb 3+ ) 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, Ce 3+ 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:Ce 3+ ,Tb 3+ phosphors showed both the blue and green emission wavelengths of Ce 3+ and Tb 3+ 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 Tb 3+ ions, due to the energy transfer (ET) from Ce 3+ ions to Tb 3+ ions. The optimal doping concentration of Tb 3+ ions in CLGB:Ce 3+ ,Tb 3+ phosphors was found to be 40 mol%. The mechanism of the ET from the Ce 3+ to Tb 3+ 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:Ce 3+ ,Tb 3+ phosphors can be a type of multicolor emitting phosphor for application in white light-emitting diodes.