In the past, an Eu3+-doped YVO4 bulk phosphor with a photoluminescence quantum yield (PLQY) of 70% was prepared by a high-temperature solid-state reaction method at 1000 °C for 5 h. In this work, ultrasmall Eu3+-doped YVO4 nanocrystals with a PLQY of 62% are rapidly synthesized by a facile ligand-assisted coprecipitation method at room temperature. The reaction is conducted under ambient conditions and is completed in 1 min. Water and ethanol are used as the solvents, while short-chain butyric acid and butylamine serve as the capping agents. As-prepared nanocrystals are characterized by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that Eu3+-doped YVO4 nanocrystals are well dispersed with a particle size of 3.6 nm. The luminescent nanocrystals prepared in this study have three advantages: room temperature preparation, high PLQY, and ultrasmall particle size. These results reveal that Eu3+-doped YVO4 luminescent nanocrystals could have high potential in lighting, display, anti-counterfeiting, and bioimaging.

LaPO 4 :Ce 3+ , Tb 3+ nanoparticles with a particle size of 2.7 nm are prepared by a facile room-temperature ligand-assisted coprecipitation method in an aqueous solution. Short-chain butyric acid and butylamine are used as binary ligands and play a critically important role in the synthesis of highly luminescent LaPO 4 :Ce 3+ , Tb 3+ nanoparticles. The absolute photoluminescence quantum yield as high as 74% can be achieved for extremely small LaPO 4 :Ce 3+ , Tb 3+ nanoparticles with an optimal composition of La 0.4 PO 4 :Ce 0.1 3+ , Tb 0.5 3+ , which is different from La 0.4 PO 4 :Ce 0.45 3+ , Tb 0.15 3+ for bulk phosphor. The energy transfer from Ce 3+ ions to Tb 3+ ions is investigated in sub-3 nm LaPO 4 :Ce 3+ , Tb 3+ nanoparticles, and Ce 3+ ion emission is almost completely suppressed. This room-temperature, ultrafast, and aqueous-phase synthetic strategy is particularly suitable for the large-scale preparation of highly luminescent LaPO 4 :Ce 3+ , Tb 3+ nanoparticles. LaPO 4 :Ce 3+ , Tb 3+ nanoparticles (110 g) can be synthesized in one batch, which is perfectly suited to the needs of industrial production.

Rare earth‐doped metal oxide nanocrystals have a high potential in display, lighting, and bio‐imaging, owing to their excellent emission efficiency, superior chemical, and thermal stability. However, the photoluminescence quantum yields (PLQYs) of rare earth‐doped metal oxide nanocrystals have been reported to be much lower than those of the corresponding bulk phosphors, group II‐VI, and halide‐based perovskite quantum dots because of their poor crystallinity and high‐concentration surface defects. Here, an ultrafast and room‐temperature strategy for the kilogram‐scale synthesis of sub‐5 nm Eu3+‐doped CaMoO4 nanocrystals is presented, and this reaction can be finished in 1 min under ambient conditions. The absolute PLQYs for sub‐5 nm Eu3+‐doped CaMoO4 nanocrystals can reach over 85%, which are comparable to those of the corresponding bulk phosphors prepared by the high‐temperature solid state reaction. Moreover, the as‐produced nanocrystals exhibit a superior thermal stability and their emission intensity unexpectedly increases after sintering at 600 °C for 2 h in air. 1.9 kg of Eu3+‐doped CaMoO4 nanocrystals with a PLQY of 85.1% can be obtained in single reaction.

We developed a room-temperature and ultra-fast Eu3+ ion doping approach for the synthesis of highly luminescent Eu-doped CaMoO4 nanoparticles. Firstly, CaMoO4 nanoparticles with a particle size of 3.9 nm are...