Sol-gel films of YBa2Cu3Ox (YBCO) were deposited by spray pyrolysis on 10 cm diameter by 0.05 cm thick polycrystalline MgO wafers. The films were deposited in 1 microm increments up to 5 microm and characterized by electrical measurements, optical and electron microscopy, and X-ray diffraction. In plane residual stresses of the films were obtained by a shadow moire interferometry technique. The YBCOMgO interface was characterized by bevel polishing and fluorescence analysis. The films contain substantial in-plane residual stresses as a result of chemical reaction of the YBCO and MgO. Cu diffuses into the MgO so that a substantial amount of Y2BaCuO5 phase forms near the interface. The largest tensile stress was 0.96 GPa in a 4 microm thick film. The stresses were highest at the center of the wafer and decreased toward the edge, and the in-plane stresses caused cracks to form. Formation of the 211 phase influenced Tc (onset) and Tc (zero resistance). The Tc onset was 78 to 92 K, and Tc (zero resistance) was 15-65 K depending on film thickness.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Surfaces and Interfaces
- Surfaces, Coatings and Films
- Metals and Alloys
- Materials Chemistry