Growth and luminescence characteristics of LiYF₄: Yb,Er nanoparticles

The morphology and size of LiYF₄:Yb,Er nanoparticles were controlled using an automatic nanomaterial synthesizer by changing the reaction time at high temperature. It was found that the nanoparticles underwent a growth and change process from small to large and then to small, and then remained at a basically stable size, reflecting the different growth stages of the nanoparticles, such as nucleation, growth, phase transition, and internal Ostwald ripening, etc. XRD analyses showed that LiF nanocrystals were first formed during the reaction process, and then all the products were converted into LiYF₄ nanocrystals. Under the excitation of a 980 nm laser, the LiYF₄:Yb,Er nanoparticles showed regular downconversion and upconversion luminescence properties, which was basically consistent with the regularity of nanocrystal growth. The experimental results showed that the upconversion luminescence and downconversion luminescence intensities of nanocrystals increasd rapidly when the synthesis time was between 0 and 50 min, and they increased slowly after the synthesis time exceeded 50 min.