Energy transfer induced color-tunable emissions from Ba2Gd5B5O17:Ce3+/Tb3+ borate phosphors for white LEDs

In this paper, Ce 3+ /Tb 3+ co-doped blue-green emitting Ba 2 Gd 5 B 5 O 17 borate phosphors were prepared for the first time. Phase purity, crystal structure, photoluminescence properties, energy transfer, and thermal stability of the as-synthesized samples were studied in detailed. The Ce 3+ ions singly doped Ba 2 Gd 5 B 5 O 17 :Ce 3+ phosphors had a broad excitation band in the 300–400 nm spectral range peaking at 345 nm, and when excited at 345 nm they exhibited a broad blue emission band in the 350–700 nm wavelength range with a maximum at 450 nm. Energy transfer process from Ce 3+ to Tb 3+ ions took place in the Ce 3+ /Tb 3+ co-doped Ba 2 Gd 5 B 5 O 17 phosphors, resulting in color-tunable emission outputs. It was found that under the excitation of 345 nm, the emission spectra of Ba 2 Gd 5 B 5 O 17 :Ce 3+ ,Tb 3+ phosphors displayed the broad blue emission band of Ce 3+ ions and the characteristic sharp green emission lines of Tb 3+ ions. Moreover, the intensity ratio of Ce 3+ blue emission to Tb 3+ green emission was adjusted by increasing the Tb 3+ doping concentration, and the Ce 3+ →Tb 3+ energy transfer mechanism was studied. Furthermore, the thermal stability of Ba 2 Gd 5 B 5 O 17 :Ce 3+ ,Tb 3+ phosphors was estimated, and the activation energy of Ba 2 Gd 5 B 5 O 17 :0.008Ce 3+ ,0.2 Tb 3+ sample was calculated to be 0.205 eV. The obtained results revealed that blue-green emitting Ba 2 Gd 5 B 5 O 17 :Ce 3+ ,Tb 3+ borate phosphors have potential usage in the fabrication of near-UV based white LEDs.