Synthesis And Magnetic Properties Of FePt Nanoparticles By Solid-state Method

FePt nanoparticle is a kind of magnetic functional material with wide application.Due to ultrahigh magnetocrystalline anisotropy constant Ku,high curie temperature,very low super paramagnetic critical size and good chemical and thermal stability,chemical ordered L10-FePt has been considered as a candidate for a new generation of high density magnetic storage materials.Therefore,the preparation of FePt with high chemical ordered has become the focus of the research.The research on the preparation of FePt nanomaterials has always been the focus of scientists.Solid-state method is a method in which all the reactant is solid,and this is one of the important methods for the preparation of new type of inorganic functional materials.In order to prepared the FePt with high chemical ordered,the Solid-state method has been adopted.And this methoud using in our experiment is improved on the basis of the traditional solid state method.Speak specifically,the inorganic salts were introduced,and the influence of experimental conditions on the morphology and magnetic properties of FePt was investigated.The FePt alloy nanoparticles have been preparaed by solid-state method,the phase composition,the products of magnetic properties,morphology and microstructure were characterized by Vibrating sample magnetometer?VSM?,X ray diffraction?XRD?,Scanning electron microscopy?SEM?,Transmission electron microscopy?TEM?,High-resolution transmission electron microscopy?HRTEM?and Physical property measurement system?PPMS?etc.The growth mechanism of Fe-Pt alloy nanoparticles was also investigated.The main conclutions are as following:1.In this work,a series of different Fe-Pt alloy nanoparticles were prepared by solid state method,and the structure and magnetic properties were characterized.It is found that the all the three ratios can achieve pure FePt phase,and when Fe : Pt=1 : 1,the obtained FePt has the largest Hc.2.In this paper,the different Fe and Pt precursors was studied.And it found that the types of precursors have a great influence on the chemical order S and magnetic properties of the FePt alloy nanoparticles.The FePt nanoparticles with best magnetic properties can be obtained when using FeCl₃^.6H₂ O and PtCl₄ as precursors.3.In the process of FePt the mixing method,calcination temperature,heating rate,salt ratio?NaCl : precursor?and other experimental conditions were optimized.The results shows that the optimal process factors are of the salt material ratio of 1500 : 1,calcination temperature of 750 ?,calcining time of 2 h.By this way,the Hc of the obtained FePt nanoparticles can reach maximum.4.By changing the molar ratio of Fe and Pt precursors,the pure Fe3 Pt nanoparticles can be obtained when Fe : Pt= 3 : 7.And when Fe : Pt= 7 : 3,the pure FePt₃ can be obtained.With the increase of calcination temperature from 350 ? to 750 ?,the structure of product gradually changed from a chemical disordered A1 structure to a chemical ordered L1₂ structure.