FePt nanoparticle hydrodynamic size and densities from the polyol process as determinedby analytical ultracentrifugation

Abstract

We have studied particle size distributions of FePt nanoparticles with analyticalultracentrifugation. The particles were made with the common polyol process by thermaldecomposition of iron pentacarbonyl and reduction of platinum (II) acetylacetonate. Thesize distribution is found to be bimodal (dual) rather than a monomodal distribution asnormally reported. The density values for these particles indicates that the smaller particles,∼7.4 nm diameter, have adensity above 4 g cm−3 whilethe larger particles, ∼16 nm, have a density of ∼3.2 g cm−3 due to a higher Fe content in the lighter particles.