Synthesis and magnetic properties of self-organized FeRh nanoparticles

Nanoparticles with various compositions of Fe-Rh have been fabricated by a solution phase chemical method and their magnetic properties characterized. After refining and size selection, the average particle size is about 2-5 nm by high-resolution transmission electron microscopy observation. From x-ray diffraction results, as-deposited FeRh nanopaticles reveal a typical chemically disordered fcc structure which can be transformed into CsCl-type structure through thermal annealing. Under selected annealing conditions, the coercivities, H-c, for FeRh nanoparticles measured at room temperature are increased, compared with that of their as-deposited states. This increasement in H-c is due to the crystallization of CsCl-type structure after annealing. Nanoparticles of Fe36Rh64 and Fe38Rh62 annealed at 600 degrees C for 6 h show the presence of the magnetic phase transitions, while those of Fe75Rh25 particles did not exhibit such a transition. (C) 2007 American Institute of Physics.