Effect of Annealing Conditions on the Structural and Superconducting Properties of Y-Ba-Cu-O Films

摘要

The effect of various annealing treatments on ion beam sputter-deposited Y1Ba2Cu(y)O(7-x)(y=3 and 5) amorphous thin films has been studied using scanning electron microscopy (SEM), X-ray diffraction and dc resistivity measurements. SEM analysis showed that the morphology of the films were clearly divided into three categories: an equiaxial grain structure, a well-oriented grid-like microstructure and a textured platelet structure. The equiaxial grain structure (random orientation according to X-ray diffraction measurements) was obtained when the film was annealed at slow heating and cooling rates in an oxygen atomosphere. The grid-like microstructure (b/c-axes oriented normal to the plane) was obtained in Cu-rich composition (y=5) by rapid thermal annealing. A textured platelet microstructure (c-axis oriented normal to the plane) was obtained using slow heating rates and by carefully controlling the gas environment at the temperature region near the orthorhombic-tetragonal transition. Thus, we have demonstrated the ability to control the morphology and orientation of the film by varying the annealing process. Keywords: Superconductors; Ceramic materials; Thin films; Electrical properties; Oxides; Electroceramics; Ceramic oxide. (JHD)