The reversible strain effect on critical current over a wide range of temperatures and magnetic fields for YBCO coated conductors

摘要

The strain effect on critical current (I c (ε)) in Y Ba 2 Cu 3 O 7 ? δ (YBCO) coated conductors was evaluated at temperatures in the range 20–83?K under magnetic fields parallel to the c -axis up to 10?T. The peaked reversible variation of I c with applied uniaxial strain was confirmed in the self-field at all tested temperatures. The strain sensitivity increases with increasing temperature, resulting in a more pronounced reversible suppression with strain at higher temperature. Interestingly, it was found that the peak strain corresponding to the maximum of I c shifts to the compressive side with decreasing temperature. Such a peak shift cannot be explained by a change in the thermal residual strain of the YBCO film, suggesting that the peak strain of the I c (ε) in YBCO coated conductors is not determined only by relaxation of the residual strain. The strain sensitivity of I c (ε) at 60?K becomes greater with increasing magnetic field, while the influence of the magnetic field is much less pronounced at 20?K. The in-field I c (ε), including the compressive strain region as well as the tensile region, shows a double peak behavior at low magnetic field at 77 and 83?K. The temperature and magnetic field effect on I c (ε) in YBCO coated conductors is discussed considering flux pinning within the grains and on grain boundaries.