<I>In-situ</I> Electron Holography Observation of FePt Nanoparticles at Elevated Temperatures

• Nakanishi Masatoshi

  Department of Quantum Engineering, Nagoya University Analysis Technology Center, FUJIFILM Corporation

• Furusawa Gen-ichi

  Analysis Technology Center, FUJIFILM Corporation

• Waki Kokichi

  Frontier Core Technology Laboratories, FUJIFILM Corporation

• Hattori Yasushi

  Recording Media Research & Development Laboratories, FUJIFILM Corporation

• Sasaki Katsuhiro

  Department of Quantum Engineering, Nagoya University

• Fukunaga Keiichi

  Japan Fine Ceramics Center

• Hirayama Tsukasa

  Japan Fine Ceramics Center

• Saka Hiroyasu

  Department of Quantum Engineering, Nagoya University

• Kuroda Kotaro

  Department of Quantum Engineering, Nagoya University

Bibliographic Information

Other Title

• In-situ electron holography observation of FePt nanoparticles at elevated temperatures

Abstract

We have developed a method to observe the magnetic field around L1₀ FePt nanoparticles by in-situ electron holography at elevated temperatures. FePt Nanoparticles with sharp size distribution and chemical homogeneity were synthesized by the reverse micelle method. The as-prepared FePt nanoparticles, which had a disordered fcc structure (A1) with the diameter centered at 6 nm, were coated with a surfactant, dispersed onto a glass plate, and heated in order to undergo a transformation from A1 to an ordered fct structure (L1₀). The particles were kept separated by the surfactant with their original diameter during annealing. A submicron-size island comprising isolated particles was removed and dispersed on an electron transparent carbon film and then magnetized along one direction. We observed a magnetic field distribution of the submicron-size island of nanoparticles by means of electron holography during heating. Although magnetization decreased between 212°C and 412°C to 25% of the initial strength at 25°C, it increased again during cooling and recovered 67% of its initial strength. However, when an island was heated to 512°C, the magnetization diminished and did not recover again during cooling. The Curie temperature (Tc) of the FePt nanoparticles was determined to be 350°C and was in good agreement with the Tc determined by bulk measurements using a VSM, which was approximately 100°C lower than the reported Tc for bulk Fe₅₅Pt₄₅.

Journal

• MATERIALS TRANSACTIONS

  MATERIALS TRANSACTIONS 48 (10), 2599-2605, 2007

  The Japan Institute of Metals and Materials

Keywords

• <I>In-situ</I> electron holography
• iron platinum alloy
• nanoparticle
• Curie temperature

Details

• CRID: 1390001204249276800
• NII Article ID: 10019955939
• NII Article ID: 130004453354
• NII Book ID: AA1151294X
• DOI: 10.2320/matertrans.md200703
• ISSN: 13475320
• ISSN: 13459678
• NDL BIB ID: 8931477
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I8931477
• Web Site: https://www.jstage.jst.go.jp/article/matertrans/48/10/48_MD200703/_pdf
• Text Lang: en
• Data Source:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
  • KAKEN
• Abstract License Flag: Disallowed