Yb3+ and Yb3+–Eu3+ luminescent properties of the Li2Lu5O4(BO3)3 phase

The luminescence of Yb3+ in the oxyborate Li2Lu5O4(BO3)3 is reported. At low temperature, in addition to the usual ytterbium infrared emission, this phosphor presents an emission in the ultraviolet (image) which corresponds to the transition from the charge transfer state (O–Yb) to the 4f levels of Yb3+. The temperature quenching Tq50% is equal to 120 K. The infrared emission studied at room temperature is located between 950 and 1100 nm. Europium emission quenching in the Li2Yb5O4(BO3)3 phase is related to Eu→Yb transfer by cross-relaxation. The reverse Yb→Eu transfer by cooperative sensitization is highlighted in the codoped Li2Lu5O4(BO3)3 compound.