Preparation Of YBCO Thin Films By Sol-Gel Process

YBCO high temperature superconductor film holds great promise for applications in infrared detector,quanta interferometer and so on.Presently the main methods of preparing YBCO films have magnetron sputtering and laser deposition.In this paper the dense YBCO with perovskite structure were expected to be prepared by Sol-Gel process.The confecting methods of sol were discussed using inorganic salt as precursors,and the FT-IR was adopted to analyse the chemical reaction and film forming mechanism of stable sol. The techniques of preparing film buffer layers on Si were studied.The SEM,TEM and XRD were adopted to study the crystal structure of films. The influences of buffer layers,substrate and heat treatment condition on the crystal structure and performance of the YBCO films were discussed. The results are listed as follows:(1) The inorganic acetate of Y, Ba and Cu were used as precursors, and diethylenetriaminejactic acid and a-methacrylic acid as complexing agents, respectively.The stable fluorine-free YBCO sol can be obtained.(2) The YSZ and STO buffer layers were prepared by Sol-Gel process on Si substrates.the YSZ and STO films could be used as the buffer layers between Si substrate and YBCO films.(3) According to the study of heat treatment process, heat treatment ambience,airflow and heat treatment temperature were considerd as the important influences on the quality and property of YBCO films.Through optimizing the process,the YBCO films were prepared on STO single crystal, and their room temperature resistance was about 200 YBCO films also were fabricated on the STO buffered Si substrate,and their room temperature resistance was about 300D.(4) Through electron diffraction, it was determined the films of YBa2Cu4O8 superconducting structure had been prepared using YSZ as buffer layers. Through XRD testing,it was indicated the YBCO powder had YBa2Cu3O7- superconducting structure.