Electrical and magnetic properties of ε-Fe3N nanoparticles synthesized by chemical vapor condensation process

epsilon-Fe3N nanoparticles synthesized by chemical vapor condensation (CVC) are covered with shells of disordered Fe3O4 phase, as observed by a transmission electron microscopy. The zero-field cooling and field cooling temperature dependence of magnetization, ac susceptibility as a function of frequency, magnetic hysteresis loops, and the temperature dependence of resistivity of the epsilon-Fe3N nanoparticles are systematically studied. The results indicate the existence of complex magnetic properties, such as superparamagnetic behavior, exchange bias, magnetic dipole interaction, and the possible coexistence of ferromagnetic and spin-glass-like states and/or disordered surface spins of the shells at low temperatures. The temperature dependence of resistivity p(T) for compacted epsilon-Fe3N nanoparticles in a temperature range of 110 K < T < 300 K can be well described by the mechanism of fluctuation-induced tunneling conduction, while that below 110 K can be ascribed to conducting electrons scattered by localized magnetic moments and impurity as well as the influence of freezing of spin-glass-like moments and/or disordered surface spins of the shells. (c) 2006 Elsevier B.V. All rights reserved.