Synthesis of Bulk and Film Yba2cu3o7-x High-temperature Superconductor By the Sol-gel Method

Bulk YBa2CU3O7-x has been prepared by the sol-gel method using metal alkoxide and metal acetate as precursors and ammonia or ethylenediamine as complexing agent. The temperature of the transformation of the gel precursor to YBa2Cu3O7-x depended on the type of precursor and the agent used for adjusting the pH. The gel synthesized from precursor alkoxide gives YBa2Cu3O7-x at lower temperature (750 degrees C for 6 h) than with acetate. The gel synthesized by different metal acetates and ammonia produces YBa2Cu3O7-x at a lower temperature than the sample prepared from acetate and ethylenediamine. From X-ray diffraction studies it appears that a relationship exists between the reactivity of the gel and the orientation of the corresponding pellet. The preliminary results from a film prepared by painting the gel on alumina and yttria-stabilized zirconia are presented. A high sintering temperature (940 degrees C for 1 h) was found to be necessary for obtaining superconductor film. The reactions between YBa2Cu3O7-x and supports were reduced by using silver as buffer. The T-on of the film prepared on the modified alumina support was 91 K and T-off was 78 K