Study On Nanoparticle Size Reference Materials

Nanoparticle material is a new type of material that appeared with the development of nanotechnology.Since it has excellent characteristics that ordinary powder materials cannot reach,it is widely used in many aspects such as catalysis,optics,medicine,etc.And it gets the attention of the countries all over the world.Due to the tiny nanoparticle size and complicated preparation process,domestic and overseas are lack of unified standards.As a result of the methods of traceability,quantity transfer and uncertainty evaluation haven't been built,the values of national nano/submicron particle size standard materials are just traced to the values of NIST microsphere standard materials.So three kinds of nanoparticle size standard materials are prepared,which includes two kinds of gold nanoparticle size standard materials and one kind of silica nanoparticle size standard material.Meanwhile,several determination methods for mono-disperse nanoparticle size are studied,such as electron microscope(EM),dynamic light scattering(DLS)and particle size analysis(PTA).Finally,the uncertainty evaluation methods are built to make sure the accuracy of results.The following is the main contents:1.Two kinds of gold nanoparticle size standard materials and one kind of silica nanoparticle size standard material are prepared,whose nominal values are 15 nm,25nm,50 nm,respectively.In the process of preparation,the analysis of experimental methods and experimental conditions,including the amount of reaction substance,the type of reaction materials,reaction time,pH and additives,are discussed in detail to find a best method.And at the end,the uniform,stable and mono-disperse nanoparticle size standard materials are synthesized.2.The method of electron microscope(EM)for determining nanoparticle size is studied.At the same time,the magnifications of the equipment TEM or SEM are calibrated by the interplanar crystal spacing of single crystal silicon or line-width reference material and the technology for measuring spacing of gratings was built with centroid method.After quantity transfer,the particle size measurements can be traced to basic physical constants or national primary length.This method has been thoroughly solved the traceability problem.At the same time,combine with image analytical method to determine nanoparticle size and particle size distribution.3.Uncertainties are evaluated in the process of determination by TEM.Meanwhile,the stability and uniformity of nanoparticle standard materials are tested by disc centrifugal sedimentation instrument.4.The IRMM invites different laboratories in the world to characterize standard material(ERM-FD101b)with calibrated instruments such as TEM,SEM,DLS,PTA.The results submitted by our laboratory are located in the final accurate values' confidence interval,which proves that measurement methods are accuracy and verifies the measurement capability of our laboratory.