Recent Advances in Chemical Synthesis,Self‐Assembly,and Applications of FePt Nanoparticles

This paper reviews recent advances in chemical synthesis, self‐assembly, and potential applications of monodisperse binary FePt nanoparticles. After a brief introduction to nanomagnetism and conventional processes of fabricating FePt nanoparticles, the paper focuses on recent developments in solution‐phase syntheses of monodisperse FePt nanoparticles and their self‐assembly into nanoparticle superlattices. The paper further outlines the surface, structural, and magnetic properties of the FePt nanoparticles and gives examples of three potential applications in data storage, permanent magnetic nanocomposites, and biomedicine.     

Synthesis and Properties of Magnetic Nanoparticles

The uniform mesoporous SBA-15 consisting of SiO2 with long-range channels Offers an excellent host material to synthesize or assemble the magnetic nanocomposites, such as Fe, Ni. In this paper, highly dispersed and uniform iron nanoparticles were incorporated into the pore channels of SBA-15 through a newly developed strategy in which some kinds of coupling agents were used to entrap the nanoparticles into the silica framework. The X-ray diffraction （XRD）, fourier transmission infrared spectroscopy （FTIR）, high-resolution transmission electronic microscopy （HRTEM） and energy dispersive X-ray spectroscopy （EDX） were performed to further identify the successful incorporation and grafting of iron. Compared with other ordinary non-assembled magnetic nanoparticles, the assembled Fe nanoparticles with the diameter even in the size range of 5～6 nm still have better magnetic properties.     

Magnetic Properties of Ni Nanoparticles and Ni（C） Nanocapsules

Structure and magnetic properties of Ni nanoparticles and Ni(C) nanocapsules were studied.The carbon atoms hardly affect the lattice of Ni to form Ni-C solid solution or nickel carbides.The large thermal irreversibility in zero-field-cooled and zero-field magnetization curves indicates magnetic blocking with a wide energy barrier.Saturation magnetization,remanent magnetization and coercivity of Ni(C) nanocapsules decrease with increasing temperature.magnetization,remanent magnetization and coercivity of Ni(C) nanocapsules decrease with increasing temperature.     

Nematic‐like Organization of Magnetic Mesogen‐Hybridized Nanoparticles

A fluid nematic‐like phase is induced in monodisperse iron oxide nanoparticles with a diameter of 3.3 nm. This supramolecular arrangement is governed by the covalent functionalization of the nanoparticle surface with cyanobiphenyl‐based ligands as mesogenic promoters. The design and synthesis of these hybrid materials and the study of their mesogenic properties are reported. In addition, the modifications of the magnetic properties of the hybridized nanoparticles are investigated as a function of the different grafted ligands. Owing to the rather large interparticular distances (about 7 nm), the dipolar interaction between nanoparticles is shown to play only a minor role. Conversely, the surface magnetic anisotropy of the particles is significantly affected by the surface derivatization.