Molten‐Salt‐Assisted Synthesis of Na 3 Bi(PO 4 ) 2 :Eu 3+ Nanoparticles with Strong Red Emission

Single phase Eu 3+ ‐doped Na 3 Bi(PO 4 ) 2 (NBPO) nanoparticles with different Eu 3+ concentrations are successfully synthesized by a molten‐salten method using Na 3 PO 4  · 12H 2 O both as reaction medium and as reactant. The influence of synthesis conditions such as the Na 3 PO 4  · 12H 2 O content, heating temperature, and time on the crystal structure of the final products is investigated by X‐ray diffraction (XRD) and scanning electron microscopy (SEM). It reveals that pure phase Na 3 Bi(PO 4 ) 2 nanoparticles with size about 100 nm are successfully achieved when the mixture (molar ratio of 1:4 between Bi(NO 3 ) 3  · 5H 2 O and Na 3 PO 4  · 12H 2 O) is heated at 180 °C for 12 h. After Eu 3+ ‐doping, NBPO:Eu 3+ nanoparticles exhibit bright red emission peaking at 620 nm under the excitation of the near ultraviolet (NUV) light. The luminescence is attributed to the electric dipole transition 5 D 0  →  7 F 2 of Eu 3+ ions. The luminescent intensity of the NBPO:Eu 3+ phosphors is strongly dependent on the Eu 3+ content and concentration quenching occurred when the Eu 3+ concentration is larger than 8 mol%, which is attributed to dipole–dipole interaction. This work provides a green way for the synthesis of phosphate‐based nanomaterials and suggests that Eu 3+ ‐doped Na 3 Bi(PO 4 ) 2 has a great potential application in the lighting and display fields.