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Residual-stress measurement of YBCO sol-gel films on polycrystalline MgO

Thesis/Dissertation ·
OSTI ID:7038971

YBa{sub 2}Cu{sub 3}O{sub x} thick films were fabricated on 10-cm-diameter polycrystalline MgO wafers by spray pyrolysis of a sol-gel solution made from metal acetates gelled in monoethanolamine. The film thickness was built up in layers of approximately 1-{mu}m thick. In-plane residual stresses were measured of each layer by a shadow moire technique. The films were characterized by electrical property measurements, optical and electron microscopy, and X-ray. The critical temperature onset ({Tc}) was from 78 to 92K, and {Tc} zero was from 15 to 65K depending on film thickness. The best critical current density is 3,100 (A/cm{sup 2}) for a small sample and 1,883 (A/cm{sup 2}) for a large wafer. The highest crack density was obtained at the center of the large wafer and corresponded to a lower J{sub c} values vary with film thickness and position on the wafer. The highest crack density was obtained at the center of the large wafer and corresponded to a lower J{sub c} region. A cation diffusion study showed that the significant Cu diffusion occurs into the MgO substrate. X-ray analysis of the films showed that the amount of the impurity phase Y{sub 2}BaCuO{sub 5} (211) varies with film thickness; as the film gets thicker, the amount of 211 was decreased.

Research Organization:
Illinois Univ., Chicago, IL (United States)
OSTI ID:
7038971
Country of Publication:
United States
Language:
English