Low-Temperature Synthesis of YBa2Cu3O7-x and YBa2Cu4O8 by Sol-Gel Method

Abstract

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