Optimization of Transport Critical Currents at 4.2 K – 20 K at Magnetic Fields Up to 31 T for MOCVD REBCO Conductors With Variable Zr and Growth Conditions

The critical current, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$I_{\mathrm{c}}$</tex-math></inline-formula>, of REBCO full-width 4 mm short samples made by metal-organic chemical vapor deposition (MOCVD), optimized for high-field applications, were measured at magnetic fields perpendicular to sample plane up to 31.2 T in resistive magnets and temperature range <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">${\text{4.2}}\,{\text{K}}$</tex-math></inline-formula>–55 K. Dependencies of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$I_{\mathrm{c}}$</tex-math></inline-formula>, critical current density (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$J_{\mathrm{c}}$</tex-math></inline-formula>), and pinning force density (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$F_{\mathrm{p}}$</tex-math></inline-formula>) on Zr doping and REBCO growth conditions were studied. SEM images of cross-section and top view of the REBCO layers for tapes with 15%, 20%, and 25% Zr doping show dense REBCO layers without secondary phases or porosity. REBCO tapes with 20% and 25% Zr doping perform better in transport <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$I_{\mathrm{c}}$</tex-math></inline-formula>(<italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T,</i><inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\mu _{o}H$</tex-math></inline-formula>) tests at 20 K and 20 T conditions than tapes with lower Zr doping and can be promising candidates for applications focusing on magnetic plasma confinement.