Site-occupancy on the luminescence properties of a single-phase Li4SrCa(SiO4)2:Eu2+ phosphor

Eu2+-doped Li4SrCa(SiO4)2 phosphor was synthesized by a high temperature solid-state reaction. There are two different crystallographic sites, namely, a Sr2+ site and a Ca2+ site in the cell of Li4SrCa(SiO4)2, which can be occupied by Eu2+ ions and will generate two emission bands. However, three different emission bands were observed in this phosphor. The first one is peaking at 433 nm with the corresponding excitation band at 250–400 nm. The second one is at 584 nm under the excitation at 395 nm, which shows lower emission intensity than that of the blue emission. The third one is at around 615 nm under the excitation at 460 nm. Analysis suggests that the 433 nm emission belongs to Eu2+ on Sr2+ site, and the 584 nm emission originates from Eu2+ on isolated Ca2+ site. The 615 nm emission may be related to Eu2+ clusters.