XPS and Magnetic Properties of CoFe<sub>2</sub>O<sub>4</sub> Nanoparticles Synthesized by a Polyacrylamide Gel Route

Abstract

Cobalt ferrite CoFe2O4 nanoparticles were prepared via a polyacrylamide gel route and were characterized by XRD, SEM, XPS and VSM. It is demonstrated that the sample (designated S1) prepared without using the cross-linking agent bis-acrylamide has an average grain size of 45 nm, while the sample (designated S2) prepared by introducing an amount of bis-acrylamide which is about 1/5 times the amount of acrylamide has an average grain size of 23 nm. The two kinds of particles are shaped like spheres. The cation distribution is determined, from Co 2p3/2 and Fe 2p3/2 XPS spectra, to be (Co0.4Fe0.6)[Co0.6Fe1.4]O4 for both the samples, where (Co0.4Fe0.6) and [Co0.6Fe1.4] represent cations in the tetrahedral and octahedral sites, respectively. Magnetic measurement reveals a saturation magnetization of 67.3 A·m2·kg−1 for sample S1 and 62.3 A·m2·kg−1 for sample S2, but a similar coercivity of about 87.5 kA·m−1 for both the samples.