Effects of heat treatments on microstructure formation in MgB 2/YSZ/hastelloy film

Satoshi Hata, Harini Sosiati, Noriyuki Kuwano, Yoshitsugu Tomokiyo, Akiyoshi Matsumoto, Masao Fukutomi, Hitoshi Kitaguchi, Kazunori Komori, Hiroaki Kumakura

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)

Abstract

Annealing processes in MgB2 films deposited on yttria-stabilized zirconia (YSZ)-buffered Hastelloy substrates were studied by transmission electron microscopy. The MgB2 films with Mg-rich compositions were fabricated at room temperature using a pulsed laser deposition (PLD) method. The as-deposited films do not exhibit clear superconducting transitions, and have inhomogeneous microstructures composed of amorphous regions and a small amount of crystalline MgB2 and MgO with several tens of nm in size. Various sizes of voids are also incorporated within the amorphous regions. After the annealing at 600 or 680°C, the films exhibit clear superconducting transitions. The amorphous regions crystallize into fine grains of MgB 2 or MgO 5-50 nm in size. The voids remain in the annealed films and their sizes depend on the annealing condition. Magnesium-and oxygen-rich layers are formed near the MgB2/YSZ interface and the film surface. It is suggested that the finer grains of MgB2 and MgO obtained by the lower-temperature annealing give a larger critical current density under a high magnetic field.

Original languageEnglish
Pages (from-to)3238-3241
Number of pages4
JournalIEEE Transactions on Applied Superconductivity
Volume15
Issue number2 PART III
DOIs
Publication statusPublished - Jun 2005

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering

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