TY - JOUR
T1 - Effects of heat treatments on microstructure formation in MgB 2/YSZ/hastelloy film
AU - Hata, Satoshi
AU - Sosiati, Harini
AU - Kuwano, Noriyuki
AU - Tomokiyo, Yoshitsugu
AU - Matsumoto, Akiyoshi
AU - Fukutomi, Masao
AU - Kitaguchi, Hitoshi
AU - Komori, Kazunori
AU - Kumakura, Hiroaki
N1 - Funding Information:
Manuscript received October 4, 2004. This work was supported in part by Nanotechnology Support Project of the Ministry of Education, Culture, Sport, Science, and Technology, Japan. S. Hata and Y. Tomokiyo are with the ASEM, Kyushu University, Kasuga 816-8580, Japan (e-mail: hata@asem.kyushu-u.ac.jp). H. Sosiati is with the HVEM, Kyushu University, Fukuoka 812-8581, Japan. N. Kuwano is with the ASTEC, Kyushu University, Kasuga 816-8580, Japan. A. Matsumoto, M. Fukutomi, H. Kitaguchi, K. Komori, and H. Kumakura are with the National Institute for Materials Science, Tsukuba 305-0047, Japan. Digital Object Identifier 10.1109/TASC.2005.848834
PY - 2005/6
Y1 - 2005/6
N2 - 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.
AB - 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.
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U2 - 10.1109/TASC.2005.848834
DO - 10.1109/TASC.2005.848834
M3 - Article
AN - SCOPUS:22044451490
SN - 1051-8223
VL - 15
SP - 3238
EP - 3241
JO - IEEE Transactions on Applied Superconductivity
JF - IEEE Transactions on Applied Superconductivity
IS - 2 PART III
ER -