Fe-Ptナノ粒子の物性と表面保護剤による表面効果

抄録

Effects of surfactants on synthesis and properties of Fe-Pt nanoparticles were investigated in the present study. Fe-Pt nanoparticles were synthesized by a polyol method using Fe and Pt organic complexes in tetraethylene glycol. Whereas the addition of Poly (diaryldimethylammonium chloride) (PDDA) or poly (N-vinyl-2-pyrrolidone)(PVP) influenced the atomic ordering of Fe-Pt nanoparticles, that of oleic acid/oleylamine did not have an effect on the formation of ordered alloy Fe-Pt nanoparticles. Surfactant-coated silica microspheres were used for the growth of Fe-Pt nanoparticles on their surfaces to investigate preferential sites for nucleation of the Fe-Pt nanoparticles. Fe-Pt nanoparticles were selectively deposited only on surfactant-coated silica microspheres although Fe-Pt nanoparticles were formed in a solution without any surfactants. When Fe-Pt nanoparticles were synthesized with silica microspheres and a surfactant such as PDDA in a reaction solution, few Fe-Pt nanoparticles were observed on the silica microspheres. These results indicate that the nucleation of Fe-Pt nanoparticles commences selectively on surfactants such as PDDA, PVP, and oleic acid/oleylamine. In particular, polymer surfactants such as PDDA and PVP influenced the atomic ordering of Fe and Pt, leading to the formation of ferromagnetic nanoparticles at room temperature even though the particle size is less than 5 nm.