Deterioration mechanism of oxide superconductor

摘要

Deterioration of oxide superconductors has been investigated by evaluating the critical current densities, J/sub c/, at 77 K and the conductivity at room temperature. The oxide superconductors were exposed to both moisture and heat cycles. The authors observed slow decreases in J/sub c/ often followed by fast decreases. The experimental results indicate that an external substance penetrates into the superconductors and brings about chemical reactions to form nonsuperconducting products so that volume expansion occurs at the site causing cracks.