New greenish-yellow and yellowish-green emitting glass phosphors: Tb3+/Eu3+ and Ce3+/Tb3+/Eu3+ in zinc phosphate glasses

A spectroscopic investigation of zinc phosphate glasses activated with Eu3+, Tb3+/Eu3+ and Ce3+/Tb3+/Eu3+ ions is performed through photoluminescence spectra and decay time measurements. Greenish-yellow light emission, with x=0.42 and y=0.50 CIE1931 chromaticity coordinates, is obtained in the 5.0% Tb(PO 3) 3-2.0% Eu(PO 3) 3 codoped zinc phosphate glass upon Tb 3+ excitation at 340 nm. Such greenish-yellow luminescence is generated mainly by the 5D4→7F6,5 and 5D0→ 7F1,2 emissions of Tb3+ and Eu3+, respectively, europium being sensitized by terbium through a non-radiative energy transfer. By codoping with 0.1 Ce(PO3)3 in addition to Tb3+/Eu3+ yellowish-green light emission with CIE1931 chromaticity coordinates, x=0.33 and y=0.48, is achieved through non-radiative energy transfer from Ce3+ to Tb3+ and from Ce3+ via Tb3+ to Eu3+ upon 280 nm excitation (peak emission wavelength of AlGaN-based LEDs).