Electron microscopy of MgB2 thin film on YSZ-buffered Hastelloy

✍ Scribed by Harini Sosiati; S. Hata; N. Kuwano; Y. Tomokiyo; A. Matsumoto; M. Fukutomi; H. Kitaguchi; K. Komori; H. Kumakura

• Publisher: Elsevier Science
• Year: 2004
• Tongue: English
• Weight: 725 KB
• Volume: 412-414
• Category: Article
• ISSN: 0921-4534
• DOI: 10.1016/j.physc.2004.01.168

✦ Synopsis

In order to understand the relationship between the microstructures and superconducting properties of MgB 2 films, analytical TEM observations have been carried out. The films were fabricated by a KrF excimer laser deposition on Hastelloy substrates precoated with YSZ (yttria-stabilized zirconia). The deposited films were annealed under Ar atmosphere at 873 K for 1 h and at 953 K for 0.5 h. The critical current densities of these films were measured to be J c ¼ 1 Â 10 5 A/cm 2 and J c ¼ 7:7 Â 10 3 A/cm 2 at 4.2 K and 10 T, respectively. The conventional TEM observation showed nanocrystalline MgB 2 and MgO of 5-30 nm in size dispersed in the films. Voids with various sizes from 10 to 60 nm were also observed in the films. Two-dimensional elemental analyses exhibited that near the MgB 2 /YSZ interface the films have a layered structure where the layers enriched with Mg and O have low B concentrations complementarily. The average sizes of the MgB 2 and MgO grains and the voids increase with the annealing temperature. The enhancement of J c value of the film annealed at 873 K may be due to smaller sizes of the MgB 2 and MgO grains and voids than those at 953 K.