Stability Investigation of Colloidal FePt Nanoparticle Systems by Spectrophotometer Analysis

FePt magnetic nanoparticle systems are an excellent candidate for ultrahigh-density magnetic recording. Monodisperse FePt nanoparticles are synthesized by superhydride reduction of FeCl₂・4H₂O and Pt(acac)₂ at 263°C under N₂ atmosphere. Transmission electron microscopy (TEM) images show monosize FePt nanoparticles with diameter of 4nm and a standard deviation of about 10%. The average distance between monodispesre particles is nearly 3nm, and oleic acid and oleylamine surround the nanoparticles as surfactants. Stability investigation of nanoparticle colloidal solution is done via spectrophotometery analysis. The results for FePt nanoparticles dispersed in hexane indicate that adding surfactants with concentration of 3×10^-3 part by volume for centrifugation stage increases the stability of FePt nanoparticles solution with concentration of 16mg/mL, about 67%.