Enhanced flux pinning in (Bi, Pb)-2223/Ag tapes by slight Pr substitution

Bi 1.8 Pb 0.35 Sr 2.0 Ca 2.1 Cu 3.1 Nd x O y (x = 0.00, 0.010, 0.020 and 0.030) superconductors were prepared in bulk form. Phase analysis by XRD, microstructural examination by SEM, superconductivity measurements at 77 K, etc were carried out to evaluate the relative performance of the samples. Both the self-field J C and J C in the presence of an applied magnetic field of the Nd-added samples are found to be much better than those of the undoped one. Also the peak value of the bulk pinning force density, F p max , of Nd-added samples get shifted towards higher magnetic fields, indicative of enhanced flux pinning strength in these samples. For the sample with Nd = 0.030, small fractions of (Bi, Pb)-2212 were found even after the last stage of sintering. Accordingly the microstructure of this sample shows considerable difference from the other samples, wherein the natural layered growth mechanism of (Bi, Pb)-2223 is disrupted by grain growth and coarsening in random directions. It is likely that Nd ions are substituting at the Ca site, and the point defects thus created act as flux pinners, enhancing the self-field J C as well as the J C -B characteristics of the Nd-added samples.

Section: Introductionmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

Enhanced flux pinning in (Bi, Pb)-2223 superconductor by Nd addition

Aloysius

Guruswamy

Syamaprasad³

2005

“…the coherence length. Various methods were used to introduce effective artificial pinning centers and to increase their number density [1][2][3][4][5]. Precipitates dispersed into the superconducting matrix are often found to be a predominant pin source.…”

Section: Introductionmentioning

confidence: 99%

Effect of nano-size ZrO₂addition on the flux pinning properties of (Bi, Pb)-2223 superconductor

Zouaoui¹,

Ghattas²,

Annabi³

et al. 2008

We investigated the microstructure and flux pinning capability of the bulk (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O y system (denoted as (Bi, Pb)-2223) with 0.0-0.3 wt% nano-size ZrO 2 particles (10-20 nm) addition synthesized by solid state reaction. Phase analysis by x-ray diffraction (XRD), granular structure examination by scanning electron microscopy (SEM), microstructure investigation by transmission electron microscopy (TEM) equipped with energy dispersive x-ray spectrometer (EDS), critical current density dependence on the applied magnetic field J c (H ) and electrical resistivity ρ(T, H ) were carried out. The results show that activation energies of vortex flux motion U (H ), critical current density J c (H ) behavior in applied magnetic field and volume pinning force density F p are enhanced by the addition of 0.1 wt% ZrO 2 . The pinning force analysis and microstructure observations indicated that the improvement of flux pinning is suggested to originate from the introduction of extrinsic pinning centers due to the formation of normal nano-sized Zr-rich phase.

“…The exponents p = 2.1 and q = 7.7 that fit the experimental data points are larger than usually reported for pinning by only point disorder (p = 1 and q = 2) or magnetic pinning (p = 0.5 and q = 1) [57,59]. An improved version of the Dew-Hughes model [57] considering different types of pinning centers acting simultaneously has been used in [60]. In this model, the pinning force can be written as F p = a 1 f 1 + a 2 f 2 + .…”

Section: Discussionmentioning

confidence: 96%

“…An improved version of the Dew-Hughes model (57) considering different types of pinning centres acting simultaneously has been used in Ref. (60). In this model, the pinning force can be written as 𝐹 𝑝 = 𝑎 1 𝑓 1 + 𝑎 2 𝑓 2 + … + 𝑎 𝑖 𝑓 𝑖 + ⋯ 𝑎 6 𝑓 6 where 𝑓 𝑖 = ℎ 𝑝 𝑖 (1 − ℎ) 𝑞 𝑖 and 𝑎 𝑖 ≥ 0.…”

Section: Discussionmentioning

confidence: 99%

Enhancement of vortex liquid phase and reentrant behavior in NiBi₃ single crystals

Rollano

Ory

Gómez

et al. 2023

We investigate the vortex phase diagram of needle shaped high quality NiBi3 single crystals by transport measurements. The current is applied along the crystalline b-axis of this intermetallic quasi-1D BCS superconductor. The single crystals show a Ginzburg-Levanyuk (Gi) parameter of about 10-7, larger by two orders of magnitude than Gi in elemental low Tc BCS superconductors. Vortex phase diagram, critical currents and pinning forces have been extracted from the experimental data. We observe (i) an enhancement of the vortex liquid phase, (ii) a reentrance of the liquid phase at low fields and (iii) an unusual magnetic field dependence of the pinning force. We suggest that these phenomena result from the interplay between pinning due to quenched disorder and the quasi-1D character of the material which could lead, for instance, to more complex pinning mechanisms at play.