Growth regularity and phase diagrams of NaLu_0.795−xY_xF₄ upconversion nanocrystals synthesized by automatic nanomaterial synthesizer

The growth regularities of nanomaterials are often concealed by the contingency of preparation. Therefore, it is always very difficult to figure out growth regularities of nanomaterials due to the accompanying undulation of products. A series of precise synthesis was performed by using an automatic nanomaterial synthesizer (ANS) in order to explore the growth regularity of complex NaREF₄ (RE: rare earth) upconversion nanocrystals (UCNCs). The use of ANS significantly enhances the experimental controllability, repeatability, and success rate. Mass experimental research exhibited that the NaLu_0.795−xY_xF₄:Yb³⁺/Tm³⁺ (x = 0−0.795) UCNCs can vary their sizes continuously in a wide range to accurately meet the experimenter’s design merely by controlling the concentration of Y³⁺. A notable growth regularity was obtained and intuitively shown in growth phase diagrams. Furthermore, in the case of having excellent monodispersity, pure hexagonal phase, and uniform morphology, the prepared UCNCs still retained superior upconversion luminescent (UCL) properties. The regular changes in UCL properties further confirmed the growth regularity of the UCNCs. After analyzing the experimental data, we found that NaLu_0.795−xY_xF₄ combined the advantages of NaYF₄ and NaLuF₄ hosts with desired sizes. These results provide a guidance for the exploration of growth regularities of other similar nanomaterials and also for the structure design of the required nanomaterials.[Figure not available: see fulltext.]