Cluster-assembled iron-platinum nanocomposite permanent magnets

Xiangxin Rui, Zhiguang Sun, Yingfan Xu, David J. Sellmyer, Jeffrey E. Shield

Research output: Chapter in Book/Report/Conference proceedingConference contribution


Exchange-spring nanocomposite permanent magnets have received a great deal of attention for their potential for improved the energy products. Predicted results, however, has been elusive. Optimal properties rely on a uniformly fine nanostructure. Particularly, the soft magnetic phase must be below approximately 10 nm to ensure complete exchange coupling. Inert gas condensation (IGC) is an ideal processing route to produce sub-10 nm clusters method. Two distinct nanostructures have been produced. In the first, Fe clusters were embedded in an FePt matrix by alternate deposition from two sources. Fe cluster content ranged from 0 to 30 volume percent. Post-deposition multi-step heat treatments converted the FePt from the A1 to L10 structure. An energy product of approximately 21 MGOe was achieved. Properties deteriorated rapidly at cluster concentrations above 14 volume due to uncoupled soft magnetic regions (from cluster-cluster contacts) and cooperative reversal. The second nanostructure, designed to overcome those disadvantages, involved intra-cluster structuring. Here, Fe-rich Fe-Pt clusters separated by C or SiO2 were fabricated. Phase separation into Fe3Pt and FePt and ordering was induced during post-deposition multi-step heat treatments. By confining the soft and hard phases to individual clusters, full exchange coupling was accomplished and cooperative reversal between clusters was effectively eliminated. An energy product of more than 25 MGOe was achieved, and the volume fraction of the soft phase was increased to greater than 0.5 while maintaining a coercivity of 6.5 kOe. The results provide new insight into developing high energy product nanostructured permanent magnets.

Original languageEnglish (US)
Title of host publicationNanoscale Magnets
Subtitle of host publicationSynthesis, Self-Assembly, Properties and Applications
PublisherMaterials Research Society
Number of pages6
ISBN (Print)9781604234145
StatePublished - 2006
Event2006 MRS Fall Meeting - Boston, MA, United States
Duration: Nov 27 2006Dec 1 2006

Publication series

NameMaterials Research Society Symposium Proceedings
ISSN (Print)0272-9172


Conference2006 MRS Fall Meeting
Country/TerritoryUnited States
CityBoston, MA

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Mechanics of Materials
  • Mechanical Engineering


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