ANNEALING STUDIES OF ULTRASONIC SPRAY PYROLYZED YBA2CU3O7-X THIN-FILMS ON VARIOUS SUBSTRATES

YBa2Cu3O7 - x films, ~3μm thick, have been grown by ultrasonic spray pyrolysis of aqueous-glycerol solutions of Y, Ba and Cu nitrates on yttria stabilized zirconia (YSZ), MgO and Al2O3 at 300 °C. After deposition, these films have been annealed under Ar and 02 atmospheres at temperatures between 850 °C and 950 °C for few minutes. To produce the best superconducting properties of the YBa2Cu3O7t-x films, various annealing parameters such as heating and cooling rates, annealing temperature, time and environment have been investigated. It was found that in the beginning of annealing an Ar environment is necessary to obtain a c-axis oriented structure of the film, a sharp superconducting transition, and to avoid microcracks in the coatings. Resistivity versus temperature measurements show that the onset and completion of superconducting transition occur at 93K and 90.5K for YBa2Cu3O7-x films on YSZ, at 85K and 81K on MgO and at 95K and 84K on Al2O3 substrates, respectively. © 1990.