Magnetic properties of few nanometers ε-Fe2O3 nanoparticles supported on the silica

Magnetic properties of epsilon-Fe2O3 nanoparticles supported on silica with the average size of few nanometers, narrow size distribution and no admixture of any other iron oxide polymorphs are investigated. The investigation of the temperature behavior of magnetization within the temperature range from 4.2 to 1000 K revealed the presence of several magnetic subsystems in the species under study. The temperatures' behavior of the magnetic moment value indicates ferrimagnetic ordering in the epsilon-Fe2O3 nanoparticles with a Curie temperature of about 800 K and points to the existence of a significant paramagnetic contribution becoming apparent at low temperatures. According to the electron spin resonance data, the particles possess superparamagnetic behavior at temperature higher similar to 120K. The model of the magnetic structure of monophase system of few nanometers epsilon-Fe2O3 nanoparticles supported on silica is proposed. (C) 2012 American Institute of Physics. [doi:10.1063/1.3686647]