2009 年 56 巻 9 号 p. 568-573
The present paper describes chemical synthesis of ordered alloy FePt nanoparticles with dispersibility into water using a water-soluble polymer ligand, poly(N-vinyl-2-pyrrolidone) (PVP), for biomedical applications such as magnetic sensing devices for diagnostics and magnetic hyperthermia for cancer therapy. Ac magnetic susceptibility takes the maximum value at a temperature near the blocking temperature of magnetic nanoparticles. The blocking temperature of the ordered alloy FePt nanoparticles with high magnetocrystalline anisotropy can be adjusted at around room temperature to improve biomedical performances even though their size is limited in the range of nanometer. The ordered alloy FePt nanoparticles are synthesized by reduction of Fe and Pt organo-metallic compounds with tetraethylene glycol using PVP as a protective agent. Influences of reaction conditions such as temperature and time on crystallite size (particle size) and magnetic properties are investigated. Furthermore, PVP concentration at the synthesis to obtain well dispersed nanoparticle-suspension is examined.