Synthesis, energy transfer and photoluminescence properties of thermal-stable multicolour-emitting Ca3Gd(AlO)3(BO3)4:Tb3+,Eu3+ phosphors

Abstract

Novel Tb3+ and Eu3+ ions co-doped Ca3Gd(AlO)3(BO3)4 (CGAB) colour-tunable phosphors were synthesized by a traditional high-temperature solid-state reaction. Their physicochemical properties were characterized by powder X-ray diffraction, scanning electron microscope, emission and excitation spectra, and decay lifetimes. Under 352 nm near-ultraviolet excitation, the characteristic transitions of Tb3+ and Eu3+ ions were observed in the emission spectra of CGAB:Tb3+,Eu3+ phosphors. Moreover, the emitting lights of CGAB:Tb3+,Eu3+ phosphors changed from green to orange then red by increasing concentration ratio of Eu3+/Tb3+, due to the energy transfer from Tb3+ to Eu3+. The energy transfer mechanism from Tb3+ to Eu3+ was calculated to be a resonant type of quadrupole-quadrupole interaction. Furthermore, the temperature-dependent emission spectra revealed that the as-prepared phosphors possessed good thermal stability with activation energy around 0.14 eV, while the internal quantum efficiency of optimal red CGAB:0.5Tb3+,0.1Eu3+ phosphor was determined to be 67.5%. Finally, by coating commercial BaMgAl10O17:Eu2+ blue phosphors, commercial (Ba,Sr)2SiO4:Eu2+ green phosphors, and as-prepared CGAB:0.5Tb3+,0.1Eu3+ red phosphors on a 365 nm near-ultraviolet-emitting light-emitting diode (LED) chip, we fabricated a prototype white LED device, which possessed good colour rendering index (CRI = 85.3) and low correlated colour temperature (CCT = 4329 K).