Small-size and high-crystallinity β-NaLuF4 nanocrystals synthesized by automatic nanomaterial synthesizer

[Display omitted] •Sub-50 nm and monodispersed β-NaLuF4: Yb3+/Tm3+ NCs were synthesized by a self-development automatic nanomaterial synthesizer (ANS).•Growth process of NaLuF4: Yb3+/Tm3+ NCs was studied with the assistance of ANS.•High-UCL sample can be obtained at relatively mild thermal temperature and long crystal growth period. Sub-50 nm and monodispersed hexagonal (β-) NaLuF4: Yb3+/Tm3+ (NLFYT) nanocrystals (NCs) were synthesized by using an automatic nanomaterial synthesizer (ANS). The ANS can not only reduce the experimental complexity, but also significantly increase the accuracy and reproducibility of the experiments. Transmission electron microscopy (TEM) analyses showed that the β-NLFYT NCs prepared at 295 °C have smaller size and better crystallinity than that of prepared at higher temperatures. Combined with upconversion luminescence (UCL) spectra, it turned out that the small-size and high-UCL β-NLFYT NCs can be obtained at relatively low reaction temperature and long crystal growth period.