Influence of Al on magnetic properties and DIAMETER DISTRIBUTION OF CARBON-ENCAPSULATED IRON NANOPARTICLES

摘要

Magnetic nanoparticles are unique materials because they have different size dependent physical properties in comparison to the same materials in the bulk [1]. The decrease of the crystallite size to a few or tens nm drastically changes their magnetic response. The smallest magnetic nanoparticles possess superparamagnetic behavior,whilst objects with diameters of tens nm may behave as single ferromagnetic domains with coercivity forces significantly higher than those of the same material in a macroscopic scale [2]. Their size is therefore viewed a crucial factor influencing their magnetic performance. Unfortunately the nanoparticles of bare metals tend towards irreversible oxidation and agglomeration. Surrounding the magnetic phases with protective materials is a well accepted route to increase their stability and preserve their specific magnetic properties.