Correlation Between In-Plane Grain Orientation and the Reversible Strain Effect on Flux Pinning in RE-$\hbox{Ba}_{2}\hbox{Cu}_{3}\hbox{O}_{7 - \delta}$ Coated Conductors

Abstract

The uniaxial pressure dependence of the critical temperature causes a reversible effect of strain on the critical current density and the flux pinning strength in many high-temperature superconductors. Recent experiments on patterned coated conductor bridges have shown that the anisotropic nature of the pressure dependence of the critical temperature of rare earth (RE)-Ba 2 Cu 3 O 7−δ (REBCO) has a major impact on the performance of coated conductors under strain. The strain effect on the critical current density is most prominent when the strain is along the [100] and [010] directions of the superconducting film, whereas it almost completely disappears when the strain is along [110]. In this paper, we investigate the correlation between the uniaxialpressure dependence of the critical temperature and the reversible strain effect on flux pinning in REBCO coated conductors. We show that axial strain has a large effect on the irreversibility field and the pinning force in coated conductors when the [100] and [010] directions of the superconducting film are aligned along the conductor axis. The magnitude of the strain effect in these conductors largely depends on the angle at which the magnetic field is applied. On the other hand, the critical temperature is not expected to change with the axial strain in coated conductors when the [110] direction is aligned along the conductor axis. Indeed, the irreversibility field and the magnetic field dependence of the pinning force of these conductors are almost independent of the axial strain for all angles at which the magnetic field is applied. The minor strain dependence of the critical current measured in these conductors could be caused by the average in-plane grain misalignment of between 6 • and 8 • , which causes a slight variation in the strain alignment with the axes of the superconducting film. The results confirm that the reversible strain effect in REBCO coated conductors is largely determined by the uniaxial pressure dependence of the critical temperature.

Effect of monotonic and cyclic axial tensile stress on the performance of superconducting CORC® wires

“…The reason for the reversible strain effect on I c to not occur in CORC ® wires is that the winding angle of the tapes varies between 30°-47°, measured normal to the CORC ® wire axis ( figure 18). The reversible strain effect in most REBCO coated conductors vanishes when strain is applied at 45°with respect to the tape axis [35,36], causing the relatively high winding strain in CORC ® wires to not affect I c . Axial stress applied to the CORC ® wire also will not significantly affect I c of the tapes, because at a tape winding angle of 45°, the stress applied along the CORC ® wire axis is also oriented at an angle of 45°with respect to the tape axis.…”

Review of progress in electromechanical properties of REBCO coated conductors for electric device applications

“…In addition, in some reports, strain response of pinning force showed similar to that of the I c -ε response under magnetic field. Similarly with F p,max , irreversibility field (B irr ) was slightly affected by strain [46]. Fig.…”

Unified Scaling Law for flux pinning in practical superconductors: II. Parameter testing, scaling constants, and the Extrapolative Scaling Expression

“…The shortcut of an extrapolative fitting equation similar to the ESE relation may also exist for superconducting materials other than Nb 3 Sn, as noted previously. This is because unified scaling is a ubiquitous phenomenon with master scaling curves demonstrated for Nb-Hf/Cu-Sn-Ga, V 3 Ga, and Nb 3 Ge (Ekin 1981 andthe references in Ekin 2006); V 2 (Hf, Zr) (Wada et al 1982), V 3 Si (Ekin 1984); Nb 3 Al (Ekin 1984, Keys et al 2002, Banno et al 2005, PbMo 6 S 8 (Ekin et al 1985), MgB 2 (Dhalle et al 2005, Bi-2223(van der Laan et al 2006, and Y-Ba-Cu-O (YBCO) (Cheggour et al 2003, 2005a, 2005b, van der Laan et al 2007, 2012. Of course, angular dependences need to be considered for the high-T c superconductors, but the essential point is that when flux pinning curves can be scaled into a master curve, one flux pinning curve can in principal predict them all.…”