Preparation of LaPO4:Ce3+,Tb3+ nanophosphors by mixed co-precipitation process and their photoluminescence properties

Nanosized Ce3+ and Tb3+ co-doped LaPO4 phosphors were synthesized by a mixed co-precipitation method using oxalic acid (H2C2O4·2H2O) and ammonium dibasic phosphate ((NH4)2HPO4) as the precipitants. The morphology, crystal structure and photoluminescence properties of the synthesized LaPO4:Ce3+,Tb3+ phosphors were investigated by thermo-gravimetry and differential scanning colorimetry, X-ray diffraction, scanning electron microscope, and photoluminescence emission spectra methods. The results showed that the pure phase of lanthanum orthophosphate can be formed with a lower calcining temperature compared to that of the traditional solid-state reaction method. LaPO4 phosphors doped with 20 mol% Tb3+ and 40 mol% Ce3+, which were calcined at 900 °C for 1 h, reached the maximum emission intensity under 265 nm excitation. The most prominent emission was at 543 nm, which corresponded to the 5D4→7F5 transition of Tb3+ ions.