LOW-TEMPERATURE SYNTHESIS OF YBA2CU3O7-X AND YBA2CU4O8 BY SOL-GEL METHOD

The 123 and 124 superconductors were synthesized by sol-gel methods at low temperature. Heat treatment was done below 800-degrees-C; neither special equipment nor additives were required. The 123 pellets, which were prepared at 650-degrees-C under vacuum condition (0.1 to 1.0 Pa) followed by annealing in flow oxygen at 750-degrees-C and 800-degrees-C, exhibited zero resistance at 70 and 80 K, respectively. Both the 124 pellets, which were prepared at 780-degrees-C in 1 atm oxygen atmosphere followed by either furnace cooling to room temperature or quenching from 780-degrees-C to liquid nitrogen temperature, had almost the same transition temperature (T(c)(onset) = 83-80 K, and T(c) (zero) = 76-69 K).