The role of particles annealing temperature on magnetorheological effect

Abstract

The spinel nanocrystalline cobalt ferrite (CoFe2O4) particles were prepared via a solgel method followed by the annealing process. Their structural, magnetic and magnetorheological (MR) properties depending upon the annealing temperature were investigated. The X-ray diffraction analysis revealed that the higher annealing temperature, the larger grain size of CoFe2O4 particles resulting in larger magnetic domains in particles. The saturation magnetization, determined via a vibrating sample magnetometry, increased with annealing temperature and, in contrast, the coercivity decreased. The rheological behavior of CoFe2O4 particles based MR suspensions determined under the small-strain oscillatory shear flow in magnetic field showed that higher annealing temperature reflects in larger changes of rheological properties. © 2012 World Scientific Publishing Company.