Switching field distribution changes during reaction-milling of iron-zinc nanocomposites

DC remanent hysteresis loops have been measured for a series of reaction-milled Fe-Zn nanocomposites. The remanence curves are characteristic of the amount of the material switched into the field direction in a given field. The derivative of the remanence curve, the SFDR, is directly related to the distribution of the size and shape of particles. For the relatively homogenous starting powder of Fe₃ O₄, SFDR=0.77, it increases to a very large value during the actual chemical reaction (after 2 hrs of milling), and it decreases to 1.00 after 9 hrs of milling, indicating that the resulting Fe particles have a wider size and shape distribution than the original powder. The change in SFDR can be used as a quick tool for characterizing the magnetic particles in the nanocomposite