Dispersion and Lorentz Microscopy of Samarium Cobalt Nanoparticles in a Polymer Matrix

Abstract

A new method for dispersing magnetic nanoparticles in a polymer matrix is described. SmCo5 nanoparticle powders are first prepared by ball milling, and then embedded in thermoplastic powder by further milling. The nanoparticle-embedded thermoplastic powder was compacted to form solid magnetic composites which were characterized by transmission electron microscopy (TEM) and by SQUID magnetometry. The conventional TEM measurements on microtomed sections of the composites showed spherical nanoparticles clearly separated from their nearest neighbors, thereby eliminating exchange interactions and greatly reducing magnetostatic interactions. Lorentz microscopy illustrated the potential for imaging single particles and determining the magnetization directions of isolated and interacting particles. Magnetic measurements on dilute samples show that the processing method does not degrade the magnetic properties of the particles.