| Summary: | Many new superconducting materials have been discovered in recent years. This includes hydrogen sulfide which superconducts at 203 K under high pressure and Fe-As based materials. To this date the copper oxide-based materials remain as the highest transition temperature superconductor under normal pressure. In this paper we discuss the use of nano-sized particle as pinning center in the Ag-sheathed high temperature superconductor tapes to enhance the transport properties. When the size d of the pinning center is between the coherence length. and the penetration depth lambda (xi < d < lambda), a stronger interaction between the pinning center and flux lines leading to higher transport critical current density, J(c) can be expected. The effect of nanoparticle with size between the coherence length and the penetration depth i.e. xi < d < lambda, Co3O4 on superconductor tapes is discussed in this paper. Three types of Bi(Pb)-Sr-Ca-Cu-O starting materials namely from co-precipitation method without Co3O4 and with 30 nm and 50 nm Co3O4 addition have been prepared. The composition of the 30 nm and 50 nm Co3O4 added samples is (Bi1.6Pb0.4) Sr2Ca2Cu3O10-(Co3O4)(0.02) and (Bi1.6Pb0.4)Sr2Ca2Cu3O10-(Co3O4)(0.01), respectively. The tapes (similar to 2-3 cm long) were heated at 845 degrees C for 100 and 150 h. All nanoparticles added tapes showed higher Jc compared to the non-added tapes. By comparing the current results with our previously reported results, the tapes with 30 nm Co3O4 sintered for 50 h showed the highest Jc at all temperatures. This work also showed that smaller magnetic nanoparticles enhanced Jc better than larger particles, A longer sintering time (> 50 h) degraded J(c).
|
|---|
