Impinging streams application in mass production of rare earth ions doped upconversion luminescence microparticles

Known as one efficient upconversion luminescent material, Rare-earth ions doped natrium yttrium fluoride NaYF 4 :Yb/Re has broad application prospects. However, due to the limitation of the existing preparation methods, it is difficult to realize industrial production. In this paper, the upconversion luminescence microparticles, rare earth ions doped Natrium Yttrium Fluoride NaYF 4 :Yb/Er, were synthesized productively by impinging stream method. Synthesis conditions were optimized as EDTA: Ln to 0.5 and NaF: Ln to 6 (Ln represents the sum of moles of Y, Yb, and Er), reacting temperature and time to 50 °C and 3 h to obtain a high yield of 99.92% and particle with good monodispersity. To get strong upconversion luminescence, the effect of the calcination temperature and the amount of EDTA were investigated. The bright upconversion emissions by excited with laser radiation at 975 nm were found at 510–690 nm. The higher the calcination temperature, the stronger the luminescence and the strongest luminescence occurs when calcined at 600 °C. And the adding of EDTA will decrease the luminescence intensity. However, the sintering of particles at high temperatures and aggregation of particles without EDTA are unfavorable for the application of the products. Based on the above considerations, the optimal calcination temperature was determined at 450 °C, and the ratio of EDTA: Ln is preferred at 0.5. The impinging stream method to prepare upconversion material has the advantages of being simple in the process and equipment, high in output, low in investment, and convenient to be applied and popularized. Highlights Mass Production of up-conversion luminescence materials is illustrated. NaYF 4 :Yb/Er microparticles were synthesized by the novel impinging stream method. Products with high yield of 99.92% and good mono-dispersity could be obtained at optimal condition. The hexagonal crystals were obtained by calcinations at 450 °C, and it can emit bright up-conversion emissions of at 510–690 nm.