Ultrasonic-assisted synthesis of core–shell structure CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb nanophosphors and their photoluminescence properties

CePO4:Tb, CePO4:Tb/GdPO4, GdPO4/CePO4:Tb and (Ce, Tb, Gd)PO4 (4–8) nm × (35–73) nm sized nanobars with the hexagonal crystal system have been obtained by ultrasonic-assisted synthesis and characterized by X-ray diffraction (XRD), FT-IR spectrum, transmission electron microscopy (TEM), photoluminescence (PL). The shell thickness of CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb core/shell structure is 1.04 nm and 1.10 nm respectively. Under ultraviolet excitation, these nanophosphors show Tb3+ characteristic emission, 5D4–7FJ (J = {6, 5, 4, 3}) and the fluorescence of CePO4:Tb/GdPO4 and GdPO4/CePO4:Tb increases superficially compared with CePO4:Tb and the co-precipitated (Ce, Tb, Gd)PO4. The photoluminescence intensity of CePO4:Tb/GdPO4 is 33 times, 7 times, 2 times as high as that of CePO4:Tb, GdPO4/CePO4:Tb and (Ce, Tb, Gd)PO4, respectively. It is worth mentioning that the increasing amount of intensity of CePO4:Tb/GdPO4 is double than that of GdPO4/CePO4:Tb. A possible formation mechanism for the fluorescent efficiency enhancement has been proposed. The results are helpful in developing effective phosphors and have potential applications in field emission display (FED) and plasma display panels (PDP).