| Fluorescent materials,especially nano-fluorescent materials,have a wide range of applications in the fields of display and bio-imaging.Among these fluorescent materials,rare-earth ion-doped upconversion nanomaterials due to its low autofluorescence,high signal-to-noise ratio,and high bio-penetration ability have wide application prospects.However,the commercial application of upconversion materials is still limited by the preparation process,especially the small-scale preparation capability and poor repeatability,resulting in a wide size distribution and unstable luminous performance between products prepared in different batches,limiting the large-scale application of the product.In this paper,we will study the influence of various experimental factors in the hydrothermal preparation route on the morphology and luminescence of upconversion nanoparticles(UCNPs),explore the reaction mechanism,and conduct amplification experiments on the basis of optimal conditions to explore the effects of amplification effects.Furthermore,we introduce the high-gravity reactor into the scale-up experimental process,trying batch synthesis of larger-scale preparation of upconversion nanomaterials,and applying the prepared upconversion nanomaterials for application.The main findings are as follows.(1)Based on the preparation of NaYF4:Yb3+/Er3+double-doped system upconversion nanoparticles,additional Gd3+ doped ions were introduced and the appropriate Gd3+doping concentration was determined at 40%.The influence of reactant concentration,surfactant concentration,reaction temperature were explored.Determined optimal reaction conditions for the preparation of rod-shaped particles with appropriate dimensions and uniform morphology was at 0.4 mmol F-addition amount,50? stirring temperature and 1:1 surfactant/solvent ratio.The prepared NaYF4:Yb3+/Er3+/Gd3+three-doped upconversion nanoparticles system dispersion showed highly visible light emission under the excitation of 980 nm near infrared light.(2)Amplified experiments based on the optimal reaction conditions.When the scale of the reaction was expanded four times,the prepared NaYF4:Yb3+/Er3+/Gd3+trible-doped system upconversion nanoparticles encountered a great change in their morphology and phase.The variance of the radial-axis average particle size distribution increased from 8.52 and 30.52 to 12.73 and 35.83 after amplification,which produced an amplification effect.On this basis of analyzing the mechanism of amplification effect,high-gravity technology was introduced to intensify the reaction process,and the influence of high-gravity level on the morphology and particle size of upconversion nanoparticles was discussed.With the increase of high-gravity level,the particle size distribution of particles significantly narrowed and became more suitable when the gravity level was 300,where the variance of the radial-axis average particle size distribution was at 5.68 and 29.76 respectively.At last,we attempted to continue to amplify the reaction to achieve the batch preparation of more than 1 g of upconversion luminescent materials with uniform morphology(average size at 45.1 nm× 152.75 nm),which could be uniformly dispersed in non-polar solvents and had good luminous properties under near infrared light excitation.(3)The prepared up-conversion nano-luminescent material was dispersed in polymer monomer for polymerization reaction,and the prepared NaYF4:Yb3+/Er3+/Gd3+@PMMA near infrared detection card could be obtained.Under the excitation of 980 nm near infrared light excitation(excitation power density at 270 mW),there was a corresponding region of visible light with clear boundaries which could be utilized in near-infrared light detection and calibration process.The prepared test card satisfied the requirements of high visible light transmittance,no need to charge and store energy which can be used in multiple scenarios and multiple environments. |
PDF Full Text Request