Effect of postannealing treatments on the electrical properties of textured Bi2Sr2.1Ca0.9Cu2O8 superconducting ceramics

Abstract

Bi2Sr2.1Ca0.9Cu2O8 superconducting ceramics have been prepared by the classical solid state route and textured using the Laser Floating Zone (LFZ) melting technique at 30 mm/h growth speed. The obtained long (more than 12 cm) textured rods were cut into 3 cm long pieces. Silver paint has been applied on each piece to produce the electrical contacts after annealing. All the samples were then annealeded at 860 ºC during 60 h and 800 ºC for 12 h with a final quench to room temperature. Samples characteristics have been determined through electrical resistivity measurements, from 77 K to room temperature, and transport critical current density at 77 K. Based on the phase diagram equilibria, half of the samples were postannealed at 750 ºC for times between 12 and 300 h and the other half at 900 ºC between 5 and 120 minutes. After postannealing, the transport electrical properties have been determined and related with the changes on microstructure.