Table 2.

Main synthetic method of UCNP and advantages and disadvantages

Main synthetic method	Examples and refs	Size range (nm)	Advantages	Disadvantages
Thermal decomposition method	NaNdF4 [44] β-NaErF4 [68]	50–500	High-quality, uniform size	Intermediate toxicity, high cost
Microemulsion method	LaF3 [99] NaYF4 [85],	40–500	Easy to operate, narrow size, high stability,	Calcination or annealing usually required
Phase transfer hydrothermal synthesis	(La-Dy)VO4 [100], YVO4 [100], NaYF4 [64],	10–1000	Good dispersion, simple procedures, tunable size	Specialized reaction vessels are needed
Sol–gel processing	GdVO4 [101] 01	30–600	Cheap raw materials, simple procedures	Broad particle size and unsuitable for bioapplication