Engineering nanocolumnar defect configurations for optimized vortex pinning in high temperature superconducting nanocomposite wires

Abstract

We report microstructural design via control of BaZrO3 (BZO) defect density in high temperature superconducting (HTS) wires based on epitaxial YBa2Cu3O7-δ (YBCO) films to achieve the highest critical current density, Jc, at different fields, H. We find the occurrence of Jc(H) cross-over between the films with 1–4 vol% BZO, indicating that optimal BZO doping is strongly field-dependent. The matching fields, Bφ, estimated by the number density of BZO nanocolumns are matched to the field ranges for which 1–4 vol% BZO-doped films exhibit the highest Jc(H). With incorporation of BZO defects with the controlled density, we fabricate 4-μm-thick single layer, YBCO + BZO nanocomposite film having the critical current (Ic) of ~1000 A cm−1 at 77 K, self-field and the record minimum Ic, Ic(min), of 455 A cm−1 at 65 K and 3 T for all field angles. This Ic(min) is the largest value ever reported from HTS films fabricated on metallic templates.

Tuning nanoparticle size for enhanced functionality in perovskite thin films deposited by metal organic deposition

“…34,45 At high temperatures, the +12BHO (d coat = 30 nm) film shows a maximum F p = 33 GN m − 3 at 77 K and 124 GN m − 3 at 65 K. Moreover, at T = 26 K, the F p of the +12BHO (d coat = 30 nm) film reaches a nearly constant~677 GN m − 3 from μ 0 H43 T up to 9 T, an F p value 10 times greater than that of Nb 3 Sn at 4.2 K. 46 Because the pinning landscape is produced by NPs, F p measured along the c-axis is actually close to the minimum value as a function of angle, not the maximum, contrary to the case of films with NRs, 45 as can be observed in the J c (θ) curves of Figures 4d-f. For the +12BZO (d coat = 150 nm) film, the BZO NPs are much less effective at 26 K than at a higher T. However, for the +12BHO (d coat = 30 nm) film, we see significant J c increases for all orientations and temperatures compared with that of the BZO MOD films, with a higher J c minimum (J c,min ) than that previously reported for any REBCO film or wire. 17,21,45,47,48 Relation between flux creep and NP density The different temperature dependence of the J c improvement (seen in the J c ratio) between BZO and BHO has its origin in the NP size (D NP ) relative to the normal-core diameter (2ξ ab ), as shown in Figure 5a. For BZO (D NP~2 5 nm), D NP /2ξ ab is 1.5 at 80 K but 44 at low temperatures, whereas for BHO (D NP~7 nm), d/2ξ ab ⩽ 1 and~2 at high and low temperatures, respectively.…”

Optimizing Nanocomposites through Nanocrystal Surface Chemistry: Superconducting YBa2Cu3O7 Thin Films via Low-Fluorine Metal Organic Deposition and Preformed Metal Oxide Nanocrystals

“…Besides rare-earth substitution 4 , irradiation 5 , template modification 6 and optimizing natural growth defects 7 , the introduction of nanoparticles or even self-aligned nanocolumns was achieved via pulsed laser deposition and metal-organic chemical vapour deposition. These socalled artificial pinning centres can be introduced in different dimensions and shapes, preventing the drastic decrease of Jc at moderate-to-high magnetic fields as well as its anisotropy with respect to the magnetic field direction.…”

Strongly enhanced vortex pinning from 4 to 77 K in magnetic fields up to 31 T in 15 mol.% Zr-added (Gd, Y)-Ba-Cu-O superconducting tapes

“…[9][10][11] Recently, their effectiveness has been observed at low temperatures [12][13][14] However, BZO nanorods are often detrimental to the critical temperature T c , and any such T c loss seriously impedes high temperature applications and blurs pinning mechanism study. 11,[15][16][17] Recently, by modifying the metal-organic chemical vapor deposition (MOCVD) growth process, we successfully incorporated a high density of BZO nanorods into REBCO thin films grown on standard commercial ion-beam assisted deposited (IBAD) templates without any T c loss, a high T c ∼ 91 K persisting up to 20 mol. % Zr-doping.…”