Multi-color emitting luminescence in an Eu3+/Tb3+ co-doping borate-phosphate system CsNa2Tb2-x(BO3)(PO4)2:xEu3+

The Tb3+ and Eu3+ emissions are compossible in Tb3+/Eu3+ co-doping phosphors to realize multi-color emissions from green, yellow, orange to red, which is practical significance for light-emitting diode (LED) lamps. Hereby, we prepared a series of Tb3+/Eu3+ co-doping phosphors CsNa2Tb2-x(BO3)(PO4)(2):xEu(3+) (x = 0, 0.001, 0.005, 0.01, 0.02, 0.04, 0.06) and determined their crystal structure by powder X-Ray diffraction method. The energy transfer of Tb3+-> Eu3+ can be verified by the overlap of Tb3+ emission and Eu3+ excitation spectra, as well as the Time-Resolved Emission Spectroscopy (TRES). The transfer efficiency of Tb3+-> Eu3+ increases from 50.4% (x = 0.001) to 89.2% (0.06), resulting in the changing emitting color from green, through yellow to red. The thermostability of yellow phosphor CsNa2Tb1.999(BO3)(PO4)(2):0.001Eu(3+) was studied from 10 K to 450 K. At 450 K, it remains 85.93% integral intensity of that at 300 K, suggesting the good thermostability. Finally, three LEDs were fabricated using a 365 nm chip and three phosphors CsNa2Tb2(BO3)(PO4)(2), CsNa2Tb1.999(BO3)(PO4)(2):0.001Eu(3+), CsNa2Tb1.96(BO3)(PO4)(2):0.04Eu(3+), which realized green, yellow and red light emissions with the CIE coordinates of (0.364, 0.570), (0.470, 0.490) and (0.662,0.336), respectively. The application significance in LED illumination or display of prepared materials is expected. (C) 2021 Elsevier B.V. All rights reserved.