A Comparative Study of the Magnetic Behavior of Single and Tubular Clustered Magnetite Nanoparticles

Single and tubular clustered magnetite nanoparticles (MNPs) were synthesized either by low-temperature coprecipitation or high-temperature hydrothermal in aqueous conditions. The size of the constitutive small nanoparticles (NPs) in two samples is almost same. Room-temperature and low-temperature magnetic measurements show that the two different MNPs have a closed saturation magnetization. In contrast, single MNPs displays a superparamagnetic but the clustered MNPs exhibit a clearly ferromagnetic behaviors, and its coercivity origin have been calculated. The results reveal that the competition of the demagnetization energy of shape and the magnetocrystalline anisotropy energy of small MNPs will increase the coercivity, and the magnetic properties are strongly influenced by the morphology of the magnetite nanocrystals.