“…The emission peaks at 545 nm, 586 nm, 591 nm, 621 nm, and 626 nm were observed, corresponding to the 5 D 4 → 7 F 5,4,4,3,3 transitions of Tb 3+ . The emission peaks at 578 nm 586 nm, 591 nm, 615 nm, 621 nm, 626 nm, 652 nm, correspond to the 5 D 0 → 7 F 0,1,1,2,2,2,3 transitions of Eu 3+ 14 . Therefore, there is a superposition of emission spectra between Tb 3+ and Eu 3+ in the range of 586–626 nm.…”