Synthesis of new green emitting phosphors based on rare earth oxycarbonates

Abstract

New green emitting phosphors, hexagonal II-type Gd 2O 2CO 3:Tb 3+ and Y 2O 2CO 3:Tb 3+, were synthesized by the simple flux method and their luminescence properties were compared with that of II-La 2O 2CO 3:Tb 3+. Bright green emission was observed in each sample and their particle sizes were in submicron scale. The excitation spectrum consisted of a broad band and some sharp peaks, which were corresponding to the 4f–5d transition of Tb 3+ and 4f–4f transition of Gd 3+ and Tb 3+, respectively. The excitation wavelength of the 4f–5d bands depends on the distance between Tb 3+ and O 2−, which affects the crystal field effect on the 5d levels of Tb 3+. Among lanthanum, gadolinium, and yttrium oxycarbonates, Gd 2O 2CO 3 is the most suitable host to obtain high emission intensity and the maximum intensity was obtained at the composition of Gd 2O 2CO 3:17 at.% Tb 3+, where it was 101% of that of a commercial LaPO 4:Ce 3+,Tb 3+ phosphor.