Crystallization behavior of Y123 films on CeO 2-buffered YSZ substrates by fluorine-free metal-organic deposition
Abstract
Epitaxial YBa 2Cu 3O 7-y (Y123) films of 200- and 850-nm thicknesses were prepared on CeO 2-buffered YSZ substrates by metal-organic deposition (MOD) using a fluorine-free metal acetylacetonate-based solution. After the heat treatment at 765 °C in an atmosphere with pO 2 = 10 Pa followed by cooling in O 2 atmosphere, the 200-nm thick film demonstrated a high critical current density ( Jc) of >4 MA/cm 2, whereas the 850-nm thick one showed a low- Jc of ∼0.3 MA/cm 2. X-ray diffraction (XRD) analyses exhibited that c-axis oriented Y123 had grown in both films. In order to investigate the crystallization behavior of Y123 films, some specimens were quenched from various intermediate stages during the annealing schedule. The XRD results showed that the c-axis oriented Y123 started to grow at a temperature as low as 730 °C. The growth of Y123 in the 200-nm thick film seems to be saturated after the temperature dwell at 765 °C for 30 min. Scanning electron microscopy exhibited that the 200-nm thick films had very smooth matrices with a number of small precipitates on the surfaces, whereas the 850-nm thick films quenched after the dwell at 765 °C had rougher surfaces and no continuous matrices. The degradation of Jc in the 850-nm thick films was probably caused by occurrence of randomly oriented Y123 grains from the inside of the film to the surface.
- Publication:
-
Physica C Superconductivity
- Pub Date:
- September 2008
- DOI:
- 10.1016/j.physc.2008.05.071
- Bibcode:
- 2008PhyC..468.1559Y
- Keywords:
-
- 74.78.Bz;
- 81.15.Np;
- High-T<sub>c</sub> films;
- Solid phase epitaxy;
- growth from solid phases