Magnetocaloric effect in ferrite nanoparticles

A comparative study of the magnetocaloric effect (MCE) is reported in two different types of chemically synthesized magnetic nanoparticle systems---cobalt ferrite and manganese zinc ferrite with mean size around 5 and 15 nm, respectively. While CoFe2O4 nanoparticles were synthesized using co-precipitation, the Mn0.68Zn0.25Fe2.07O4 (MZFO) nanoparticles were prepared by reverse micelle technique using AOT as surfactant. Our results indicate that the change in entropy with the change. in applied magnetic field (dS/dH) is reasonably large for this class of nanoparticles and has a wide distribution over a broad temperature range covering the region above and below the blocking temperature. The maximum entropy change is influenced by the particle size, overall distribution in anisotropy and magnetic moments. (c) 2006 Elsevier B.V.-All rights reserved.