Enhanced low-temperature critical current by reduction of stacking faults in REBCO coated conductors

Abstract

The effect of stacking faults (SF) on flux pinning and critical current (Ic) in rare earth based coated conductors was investigated. The SF density in YBa2Cu3O7−δ (YBCO) films with and without Dy addition, produced by metal organic deposition, was modified by altering the oxygenation temperature. A detailed microstructural analysis of the coated conductors was performed by x-ray diffraction, scanning and transmission electron microscopy and energy dispersive spectroscopy, and the observed defect population was correlated with both the self-field and in-field Ic. We report that the best self-field Ic was obtained for samples having a low SF density, in spite of the SF being effective flux pinning defects at 77 K for magnetic fields applied within the ab plane. We also show that the SF have no observable flux pinning effect at low temperatures. This study demonstrates that for devices operated at low temperatures, the elimination of SF in the conductor wires is essential to attain higher Ic.

Atomically imaged crystal structure and normal-state properties of superconducting Ca10Pt4As8Wang1, Jin2, Tao3 et al. 2019Phys. Rev. B4110View full textAdd to dashboardCite

“…4, which reveals the distribution of SFs and their thicknesses and angles with respect to the regular structure. Clearly, stacking faults induce lattice distortions, creating strain [21], pinning [22], and charge redistribution [23] in the crystal. In Fig.…”

“…The PtAs planar spacing shows slight changes (~1%) at SFs. These distortions will have marked impact on physical properties including superconducting transition temperature [17][18][19][20][21][22][23][24][25][26][27][28]. As a distortion-free system would result in the maximum T c , the existence of SFs clearly reduces the superconducting transition temperature.…”

Significant improvement of the critical current of MOD-derived YBa2Cu3O7-δ -coated conductors by post-annealing treatment

“…The peak broadening is known to be related to Y124-type SFs, which could be introduced by annealing treatments. 11,12,[15][16][17] The broadening degree is used to quantify the density of Y124type SFs, 11,15) indicating that YBCO tapes with larger broadening (00l) peaks have a higher density of Y124-type SFs. As shown in Fig.…”

Superconducting HfO2-added solution-derived YBa2Cu3O7 nanocomposite films: the effect of colloidal nanocrystal shape and crystallinity on pinning mechanism

“…Shorter stacking faults are more effective as pinning centers because they cause more dislocations (the real pinning center) per unit of area. The formation of stacking faults can be originated from the decomposition of Cu-containing impurity phases (such as Ba-Cu-O) during the oxygenation process [27][28][29], a follow-up research should be carried out varying the oxygenation temperature to increase the stacking faults density in the YBCO matrix with nanocrystals. We are also convinced that the type of nanocrystals (composition, shape, crystallinity, …) play a role during the formation of stacking faults.…”