CaYGaO4 olivine-based green and red downconversion phosphors

Abstract

Recent advances in displays, LED lighting, and dosimetry have fueled the development of new downconversion phosphor materials. Here we present two series of novel downconversion phosphors based on a recently reported ordered olivine type oxide, CaYGaO4. The phosphors were synthesized using conventional high-temperature solid-state reactions. Yttrium in the parent compound was partially substituted with trivalent europium and terbium, in concentrations ranging from 0.5 to 20 mol. %. Excitation in the UV region resulted in predominant visible emissions at orange-red and green when doped with Eu3+ or Tb3+, respectively. At room temperature, the europium-doped phosphors exhibited a strong emission band at 612 nm and several weaker bands in the green, yellow, and red region of the visible spectrum. Terbium-doped samples showed an intense green band at 551 nm with several weak bands in the orange and red regions. Below room temperature, the terbium series also showed weak emission band(s) in the blue, which were quenched at terbium concentrations ranging between 2.0 and 5.0 mol. %. Among the two series of phosphors, Eu3+- containing samples exhibited better stability against thermal quenching in the 100–600 K temperature range. These phosphors also exhibited concentration quenching while Tb-doped phosphors did not.