Improvement of weak links between grain boundaries of polycrystalline YBa2Cu3O7-y by excess Ba

Abstract

The dc field dependencies of the ac susceptibility χ″ have been studied in polycrystalline samples of YBa2+xCu3O7‐y with x‐values ranging from 0 to 0.2. Data on χ″ versus T show the expected intergranular coupling peak at the temperature Tp. For a specific dc field Tp is found to increase with x varying from 0 to 0.10, and to decrease sharply at x > 0.10. Moreover, the transport critical current density Jct of samples increases with x up to 0.10. According to this evidence it can be concluded that a certain excess of barium in YBa2 + xCu3O7‐y improves the weak links at grain boundaries.

The Influence of Nano-SiC on the Flux Pinning of YBa2Cu3O7—y/Nano-SiC Composites

“…According to these evidences, we infer that an appropriate amount of nano-SiC particles leads to additional effective flux pinning centers. These centers can enhance the flux pinning capacity of the superconductors YBa 2 Cu 3 O 7Ày and improve their critical current densities J c at temperature 5 K. This result is well coincident with our previous works [19,20].…”