Structure and Magnetic Properties of Iron/Iron-Oxide Nanoparticles Prepared by Precipitation from Solid State Solution

The influence of precipitation temperature on structural and magnetic properties of iron/iron-oxide nanoparticles is investigated. Nanoparticles were prepared by precipitation of γ-Fe precipitates in Cu-Fe solid solution and subsequently isolated by matrix dissolution. Precipitation annealing temperatures were 773, 873, and 973 K. Nanoparticles core-shell structure and morphology were characterized by X-ray diffraction, high-resolution transmission electron microscopy, and selected area electron diffraction. These measurements showed that average diameter of nanoparticles increases with precipitation temperature from 8.5 nm to 20.5 nm. The measurements of magnetization as a function of temperature and applied field have been performed by SQUID magnetometer in temperature range from 5 K to 200 K.