Preparation Of Rare Earth Doped Upconversion Luminescent Nanomaterials By High-gravity Method And Basic Study On Its Application

With the wide application of luminescent materials,and the increasing demand of luminescent materials,the research of luminescent materials has attracted much attention.The common luminescent materials include organic dyes,semiconductor quantum dots,metal nanoparticles and rare-earth doped upconversion luminescent nanomaterials(UCNPs),etc.The rare earth doped upconversion luminescence nanomaterials because of its large Stokes shift,long fluorescence lifetime and unique luminescence properties have attracted much attention.At the same time rich rare-earth resources in China,has a very important significance to develop rare-earth refined products.The status of preparation of upconversion luminescence nanomaterials is harsh conditions,high requirement of gas environment,high temperature and the size distribution of the upconversion luminescent nanomaterials is wide and inhomogeneous.In order to solve the above problems,the high gravity reaction rotation packed bed was introduced into the preparation process.In this paper,the high gravity method is combined with the traditional co-precipitation method and hydrothermal method respectively to prepare the upconversion luminescent nanomaterial with gadolinium oxide and sodium yttrium fluoride as the substrate.The effects of preparation conditions on the morphology and particle size of upconversion luminescent nanomaterials were studied,and their basic applications were explored.The main research contents and conclusions were as follows:The upconversion luminescent nanomaterials based on gadolinium oxide were obtained by the combination of high gravity technology and traditional co-precipitation method.The feasible experimental steps were explored,and studied the effects of preparation conditions on the morphology and particle size of upconversion luminescent material.The optimum preparation conditions are as follows:rotating speed of rotation packed bed is 2000 rpm(high gravity level is 279 g),reaction temperature is 90 ℃ and reaction time is 2 h.The average particles size of the upconversion luminescent nanomaterials is about 70 nm.Compared with traditional co-preparation method,the particle size of the product(350 nm)was reduced by 75%.Modified by PEG,the modified product was dispersed in waterborne polyurethane to form a transparent film with good permeability and upconverison luminescence property.Upconversion luminescent nanomaterials based on sodium yttrium fluoride were obtained by combining high gravity technology with traditional hydrothermal method.The feasible experimental steps were explored and the effects of preparation conditions on the morphology and particle size of upconversion luminescent nanomaterials were studied.The optimum preparation conditions are as follows:rotating speed of rotating packed bed is 2500 rpm(high gravity level is 436 g),hydrothermal reaction temperature is 200 ℃ and the reaction time is 2 h.The prepared upconversion luminescent nanocrystalline materials are of uniform particle size and smaller than 20 nm.Dispersed the product into the chloroform,and mixed the dispersion with PVB to form a transparent film which has excellent upconverison luminescence properties.The product was modified by DSPE-mPEG so that it could be dispersed in water.