PREPARATION AND CHARACTERIZATION OF SUPERCONDUCTING YBA2CU3O7-X THICK-FILMS FROM POWDER OF NONHOMOGENEOUS PARTICLE-SIZE

YBa2Cu3O7-x green sheets were successfully fabricated by a tape castin g method. A non-homogeneous-particle-size superconducting powder, with grain size in the range 0.5 to 50 mum, was used. The tapes were sinte red from 900-degrees to 1000-degrees-C and characterized for shrinkage , bulk density, microstructure, phase composition and critical tempera ture. Shrinkage and bulk density both increased with sintering tempera ture, but the samples showed some difficulties to attain high densitie s. To support that, SEM images indicated the presence of macropores in the microstructure of the specimens for all sintering temperatures. T he orthorhombicity and the oxygen content of- the YBa2Cu3O7-x samples went through a maximum at 975-degrees-C. All samples sintered above 90 0-degrees-C were superconducting at the temperature of liquid nitrogen . The onset temperature and the zero resistivity temperature didn't de pend on sintering temperature.