Study On Low-dimensional FePt Nanomaterials Synthesized By Using Phase Transfer Catalysis

The low-dimension FePt nanomaterials with Ll0 structure have excellent magnetic properties,biological compatibility and catalytic performances.Therefore,the FePt nanomaterials have wide applications,such as high density magnetic storage,chemical catalysis and biomedical engineering and so on.The properties of low dimensional nanomaterials mainly depend on their ingredient,structures,morphology and size.However,up to now,how to prepare the FePt nanomaterials with controllable size and morphology is still a puzzling problem for researchers.For this reason,we proposed a novel method to synthesize FePt nanomaterials.In this method,a phase transfer catalyst(DB24C8)was introduced into the preparation of FePt nanomaterials,and low-cost,non-toxic,environment-friendly FeCl2·4H2O and H2PtCl6·6H2O were employed as precursors.The phase transfer catalyst could make the reduction easily,and the reaction more controllably.It's expected to find a new low-cost and environment-friendly path to fabricate controllable low-dimensional FePt nanomaterials.In this work,the influences of different reaction conditions(precursors' ratio,reaction temperature and time,and the type and adding amount of surfactants and reductants)on the morphology and size of FePt nanoparticles were investigated.The growth mechanism of coral-like FePt was also discussed.The main results and conclusions are as follows:(1)The sphere-like and coral-like low-dimension FePt nanomaterial with fcc structure and good dispersion could be synthesized by phase transfer catalyst method.The composition of FePt nanomaterial could be tuned by modifying the ratio of precursors.When the molar ratio of FeCl2·4H2O to H2PtCl6·6H2O is 5:3,Fe,Pt atomic ratio of the synthesized materials is about 1:1.(2)Reaction time has certain influence on FePt nanomaterials.In the beginning of the reaction,average size of the FePt nanopartical rapidly increased,and then the average size hardly changed after one hour.The sample synthesized with ten hour's reaction has the best distribution.The reaction temperature has great influence on the morphology of FePt nanoparticals.There are some large Fe3O4 nanoparticals and sphere-like FePt nanoparticals in the prepared nanoparticles at 80?.With the increase of reaction temperature,the Fe3O4 nanoparticals disappeared,only FePt nanoparti cals could be synthesized,and the morphology of nanoparticle changed from sphere-like to coral-like.(3)FePt nanomaterials growth mechanism has been discussed through analyzing the HRTEM photos.We believe that the crystal nucleus' growing along the direction of<100>is the main reason of coral-like FePt nanoparticles.The surfactants might favor to adsorb on(111)of the FePt nanoparticle,which could hinder the growth along the direction of<111>and make the crystal nucleus grow into rod-like and coral-like.(4)The type and adding amounts of reductants have important influences on low-dimension FePt nanomaterials.With the increasing of the adding amounts of 1,2-propylene glycol and 1,2-hexadecenediol,the diameter of the FePt nanoparticles increased.The diameter of FePt nanoparticles relates to the amount of reductants 1-octadecene.(5)The type and adding amounts of surfactants have obvious influences on low-dimension FePt nanomerials.The surfactant oleic acid leads to sphere-like nanoparticles,and the surfactant oleyamine results in coral-like nanoparticles.Combined addition of surfactant oleic acid and oleyamine has a tougher interaction on nanoparticles.The morphology of the FePt nanoparticles can be controlled by modifying the anount of oleic acid and oleyamine.(6)The result shows that the surfactants with amine functional group lead to the appearance of Fe2O3 or Fe3O4 during the reaction.The reason is that the amine functional group,as an electron donor,prefers to bind to Pt via a coordination bond,and hardly bind with Fe.At the same time,the long hydrocarbon chain will prevent Fe from approaching Pt.In this case,there are Fe nanoparticles to form during the reaction,and then Fe nanoparticles will be oxidized to Fe2O3 or Fe3O4 in the air.