| Summary: | 碩士 === 國立交通大學 === 材料科學(工程)研究所 === 81 === The present work reports a study of the effects of the
deposition conditions on the microstructure and superconductive
properties of YBCO thin films formed by DC magnetron sputtering
plasma, and the critical temperatures were determined by four-
probe method. The films were c-axis preferentially oriented
with respect to (001) MgO surface at substrate temperatures
680-700 C. The resputtering effect of oxygen can be greatly
reduced with a high argon-oxygen ratios and a high gas
pressures. Although X-ray diffraction shows a definite c-axis
alignment normal to the substrate plane, futher analysis
reveals that a-axis alignment normal to the substrate plane,
and numerous second phases are also observed. The second phases
including CuO and Y2O3 are identified by energy dispersive X-
ray spectrometer and the detailed microstructure are analyzed
by transmission electron microscopy. In our work, YBCO thin
films on MgO substrate attain a Tc (R=0) of 83 K and Jc of 10 5
A/cm2 at 60 K.
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