Reversible Strain Dependence of Critical Current in 100 A Class Coated Conductors

TLDR

The study investigates how strain affects the critical current of YBCO and DyBCO coated conductors with various buffer layers on Hastelloy, and discusses the microscopic origins of observed differences. The authors examined strain effects on critical current by measuring YBCO and DyBCO coated conductors with various buffer layers on Hastelloy substrates. The critical current peaks at opposite strain signs for YBCO and DyBCO, and its reversible variation depends on buffer layer, with IBAD‑CeO₂/YSZ YBCO recovering from 0.30% strain while ISD‑MgO tapes irreversibly degrade below 0.22%; quenching occurs near the composite tape’s yield strain (~0.30%).

Abstract

The strain dependence of the critical current was studied for YBCO and DyBCO coated conductors with different buffer layers on Hastelloy substrates. A maximum of I/sub c/ was observed for both the YBCO and DyBCO tapes, however the sign of the strain at the I/sub c/ peak was opposite for the two superconductors. A reversible variation of I/sub c/ with applied strain was found and the reversible strain limit was observed to depend on the buffer layer. For the IBAD-CeO/sub 2//YSZ buffered YBCO tapes, I/sub c/ recovers reversibly when the applied strain is reduced starting from 0.30%. For those with an ISD-MgO buffer layer the irreversible degradation starts at a strain less than 0.22%. The reason for this difference is discussed based on microscopic observations. Quenching occurred during V-I measurements after the applied strain exceeded 0.30%, which is close to the yield strain of the composite tape.