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 a lkoxide 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 ag ent used for adjusting the pH. The gel synthesized from precursor alko xide gives YBa2Cu3O7-x at lower temperature (750 degrees C for 6 h) th an with acetate. The gel synthesized by different metal acetates and a mmonia produces YBa2Cu3O7-x at a lower temperature than the sample pre pared from acetate and ethylenediamine. From X-ray diffraction studies it appears that a relationship exists between the reactivity of the g el and the orientation of the corresponding pellet. The preliminary re sults from a film prepared by painting the gel on alumina and yttria-s tabilized zirconia are presented. A high sintering temperature (940 de grees C for 1 h) was found to be necessary for obtaining superconducto r 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.