Y2BaCuO5 Addition and Its Effects on Critical Currents in Large grains of YBa2Cu3O7-σ: A Quantitative Microstructural Study

1995 ◽  
Vol 411 ◽  
Author(s):  
Manoj Chopra ◽  
R. L. Meng ◽  
C. W. Chu ◽  
Siu-Wai Chan
Keyword(s):  
Critical Current ◽  
Flux Pinning ◽  
Critical Currents ◽  
Pinning Force ◽  
Electrical Characteristics ◽  
Volume Percent ◽  
Initial Volume ◽  
Maximum Value ◽  
Melt Texturing ◽  
Flux Pinning Force

ABSTRACTThe addition of Y2BaCuO5 (211) particles to large grain Yba2Cu3O7−δ (Y123) has significantly improved the critical current (Jc) in this material. Here a systematic quantitative analysis on the effect of the measured 211 present in large grains of Y123 has been performed, after the process of melt texturing, both on a microscopic and a nanoscopic scale with a systematic variation of the initial volume percent of 211 addition. From the correlation between critical current measurements and quantitative microscopy of both (001) and (110) sections, a maximum value of weighted Jc is observed corresponding to a measured Y123 volume percent of 20%. Although an increasing addition of 211 is effective in producing efficient flux pinning sites in the Y123 matrix, percolation paths in the Y123 matrix become limited for supercurrent. Accounting for the loss of liquid phase, we estimate an optimum initial volume of 211 for highest Jc to be 40%. Further correlation between the Jc and the true flux pinning force (Fp) shows a maximum pinning force for an initial 211 addition of 40%. However the pinning efficiency of the superconducting Y123 matrix is found to improve with an increasing 211 addition. Hence an optimum amount of 211 addition is essential for obtaining the best possible electrical characteristics in the superconducting composite.

Y2BaCuO5 addition and its effects on critical currents in large grains of YBa2Cu3O7–δ: A quantitative microstructural study

1996 ◽  
Vol 11 (7) ◽  
pp. 1616-1626 ◽  
Author(s):  
Manoj Chopra ◽  
Siu-Wai Chan ◽  
R. L. Meng ◽  
C. W. Chu
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Crack Opening ◽  
Critical Currents ◽  
Interparticle Spacing ◽  
Pinning Force ◽  
Volume Percent ◽  
Initial Volume

The addition of Y2BaCuO5 (211) particles to large grain melt textured YBa2Cu3O7–δ(Y123) has significantly improved the critical current density (Jc) of this material. Here, a systematic quantitative analysis on the effects of the 211 addition was performed on a microscopic scale with a systematic variation of the initial volume percent of 211. From the correlation between critical current measurements and quantitative microscopy of both (001) and (110) sections, a maximum value of Jc is observed, corresponding to a measured Y123 volume percent of 20% ± 3%. Accounting for the loss of liquid phase for the present processing, the corresponding optimum initial volume of 211 for the highest measured Jc is 40%. Further comparison between the weighted Jc and the true flux pinning force (Fp) also shows a maximum pinning force for an initial 211 addition of 40%. Although the weighted Jc starts to decrease with an initial 211 volume of above 40%, the pinning efficiency at higher magnetic fields (2–4 T) of the superconducting Y123 matrix was actually improved with an ever increasing 211 addition to at least 50%. Though an increasing addition of 211 is effective in producing efficient flux pinning sites in the Y123 matrix, percolation paths in the Y123 matrix become limited for supercurrent. Hence, a measured 211 volume corresponding to 80% 211 is proved to give the best possible critical current density. Furthermore, crack opening and crack spacing of the superficial cracks are found to decrease with an increasing 211 addition and with a decreasing 211 interparticle spacing. The penetration and surface length of each of these superficial cracks are hence reduced, which leads to a better electrical connectivity in the Y123 matrix.

scholarly journals Increased flux pinning force and critical current density in MgB2 by nano-La2O3 doping

2020 ◽  
Vol 756 ◽  
pp. 012019
Author(s):  
Danlu Zhang ◽  
Fang Wan ◽  
Michael D. Sumption ◽  
Edward W. Collings ◽  
CJ Thong ◽  
...  
Keyword(s):  
Critical Current Density ◽  
Critical Current ◽  
Current Density ◽  
Flux Pinning ◽  
Pinning Force ◽  
Flux Pinning Force

TEMPERATURE SCALING OF THE FLUX PINNING FORCE FOR SmBa2Cu3O7-x SINGLE CRYSTAL

2005 ◽  
Vol 19 (01n02) ◽  
pp. 55-58
Author(s):  
L. ZHANG ◽  
G. LIU ◽  
X. LENG ◽  
X. B. XU ◽  
S. Y. DING ◽  
...  
Keyword(s):  
Single Crystal ◽  
Flux Pinning ◽  
Scaling Law ◽  
Force Density ◽  
Pinning Force ◽  
Pinning Mechanism ◽  
Maximum Value ◽  
Temperature Scaling ◽  
Pinning Force Density ◽  
Flux Pinning Force

Magnetic critical current density was measured at various temperatures and fields for SmBa 2 Cu 3 O 7-x single crystal. Pronounced second peaks were observed at intermediate fields and temperatures. Normalized pinning force density [Formula: see text] exhibited a clear scaling law when H was normalized by H max where the pinning force density has the maximum value. This is an indication that a single pinning mechanism exists in the investigated temperature region.

Superconducting Properties and Flux Pinning in Liquid Quenched Nb-Ga Alloys

1981 ◽  
Vol 8 ◽  
Author(s):  
Gregory B. Clemente ◽  
F. Habbal ◽  
J. Bevk
Keyword(s):  
Critical Current ◽  
Flux Pinning ◽  
Scaling Law ◽  
Stoichiometric Composition ◽  
Upper Critical Field ◽  
Pinning Force ◽  
Microstructural Characteristics ◽  
Current Densities ◽  
Two Peaks ◽  
Flux Pinning Force

ABSTRACTNb75−xGa25+xtapes (1≤ x ≤ 6) were prepared by liquid quenching technique in an argon atmosphere. The transition temperature Tc, upper critical field Hc2 and critical current density Jc were measured in both as-quenched and annealed samples. The values of Tc (onset) ranged from 16.5 to 18.0K in the asquenched samples and increased upon annealing up to 20.0 K. Similar increase was also observed in the values of Hc2 (4.2 K) from ∼190 kOe to values higher than the attainable field of 220 kOe. For annealed samples near stoichiometric composition, Hc2 was estimated to be higher than 300 kOe. The critical current densities of these tapes are relatively low [Jc (4.2 K) ≤ 2 × 104A/cm2] compared to other melt-quenched A-15 compounds. Flux pinning force, FP, does not obey a single scaling law. The existence of two peaks in FP at low temperatures and of only one peak at 13.4 K for 1 ≤ x ≤ 4 is discussed in terms of the microstructural characteristics of the samples.

Angular dependence of the critical current density and the temperature scaling of the flux pinning force in YBCO thin film

2018 ◽  
Vol 56 (2) ◽  
pp. 754-759
Author(s):  
Abdelhalim Hafid ◽  
Ahmed Taoufik ◽  
Abella Bouaaddi ◽  
Hassan Elouaddi ◽  
Ahmed Tirbiyine ◽  
...  
Keyword(s):  
Thin Film ◽  
Critical Current Density ◽  
Critical Current ◽  
Angular Dependence ◽  
Current Density ◽  
Flux Pinning ◽  
Pinning Force ◽  
Ybco Thin Film ◽  
Temperature Scaling ◽  
Flux Pinning Force

The effects of sintering temperature on superconductivity of MgB2 prepared by hot pressing

2020 ◽  
Vol 34 (04) ◽  
pp. 2050012
Author(s):  
Qi Wang ◽  
Lei Li ◽  
Yong Zhao ◽  
Hong Zhang ◽  
Yong Zhang
Keyword(s):  
Hot Pressing ◽  
Flux Pinning ◽  
Sintering Temperature ◽  
Pinning Force ◽  
Superconducting Properties ◽  
Critical Transition Temperature ◽  
Maximum Value ◽  
Different Temperatures ◽  
Magnetic Flux Pinning ◽  
Flux Pinning Force

The [Formula: see text] superconductor bulks were prepared by hot-pressing under the pressure of 55 MPa at different temperatures of 650[Formula: see text]C, 700[Formula: see text]C, 800[Formula: see text]C, 900[Formula: see text]C, 1000[Formula: see text]C, respectively, and the hot-pressing effects on the superconducting properties of [Formula: see text] bulks were investigated. The density of bulk samples increased with the rise of sintering temperature and the density reached to the maximum value when the sintering temperature rose to 1000[Formula: see text]C. For the sample sintered at 1000[Formula: see text]C, the critical transition temperature ([Formula: see text] reached the highest value of 38.8 K despite the high content of [Formula: see text] (30.62 wt.%). However, the critical current density ([Formula: see text] did not increase with the increase in the density and [Formula: see text]. The sample sintered at 700[Formula: see text]C maintained the high superconducting volume and had a small grain size, thus providing the best magnetic flux pinning force and [Formula: see text]. An effective hot-pressing process to improve [Formula: see text] might be the way to prepare by further increasing the density of sintering samples at 700[Formula: see text]C.

Macrosegregation of Y2Ba1Cu1O5 particles in Y1Ba2Cu3O7−δ crystals grown by an undercooling method

1996 ◽  
Vol 11 (4) ◽  
pp. 795-803 ◽  
Author(s):  
A. Endo ◽  
H. S. Chauhan ◽  
T. Egi ◽  
Y. Shiohara
Keyword(s):  
Growth Rate ◽  
Flux Pinning ◽  
Faraday Effect ◽  
Growth Direction ◽  
Pinning Force ◽  
Garnet Film ◽  
Iron Garnet ◽  
Flux Pinning Force ◽  
Good Agreement ◽  
Iron Garnet Film

Macrosegregation of Y2Ba1Cu1O5 (Y211) particles was observed in Pt-added Y1Ba2Cu3O7−δ (Y123) crystals grown by an undercooling method. It was found that the macrosegregation of Y211 particles depended on the growth direction and the growth rate (R) as a function of undercooling (ΔT). The amount of Y211 particles in Y123 crystals grown at large R was larger than at small R. Also, the amount of Y211 in Y123 growing along the a-direction was larger than that along the c-direction. Further, it was noted that the smaller Y211 particles in size were distributed in Y123 grown at large R. These phenomena could be at least qualitatively explained by the prevalent trapping/pushing theory. In the direct observation of magnetic flux with the Faraday effect of iron garnet film, the flux pinning force was found to be in good agreement with the macrosegregation of Y211 particles.

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