Critical current density and microstructure of c-axis-oriented Bi2Sr2CaCu2Oχ and (Bi, Pb)2Sr2Ca2Cu3Oχ superconducting tapes

The anisotropy of the current-carrying behaviours and the effects on it of thermomechanical treatment were investigated for Ag-sheathed Bi(Pb)-Sr-Ca-Cu-O superconducting tapes using DC transport electric and magnetic measurements. With thermomechanical treatments, the transport critical current density J ct and irreversible moment m and their anisotropy with respect to θ (the angle between magnetic field and the normal of the tape surface) increase. This is attributed to the increase of the intergrain critical current density, which is closely related to the development of the c axis texturing of BPSCCO grains. For the tape with J ct ∼ 1.5 × 10 4 A cm −2 , the anisotropic behaviour of both J ct and J cm (magnetic critical current density) was compared. Both the I -V relation in the transport measurements and the magnetic moment relaxation in the magnetic measurements can be well fitted by power laws, i.e., V = AI n and m = Bt −p respectively. n and 1/p are related to the flux pinning potential U e . These indicate that U e can be well described by U e = U 0 ln(J c0 /J ). The value of n can be fitted by n ∝ H −µ and varies with θ periodically. The higher J ct , the larger the n value.

“…Experimental points fall on a single smooth curve. This is consistent with others' results in BPSCCO/Ag tapes [19,23] and BSCCO 2212 films [20].…”

Section: The Current-carrying Characteristics Of the Rppp Samplesupporting

confidence: 93%

“…As shown in figure 5 J ct (θ ) of RPPP has a strong anisotropy as for other reported BPSCCO/Ag tapes with highly c-axis-textured grains [12,19,23] and is also qualitatively similar to the film of 2212 [20].…”

Section: The Current-carrying Characteristics Of the Rppp Samplesupporting

confidence: 72%

The current-carrying anisotropy and the effects on it of thermomechanical treatments for Ag-sheathed Bi(Pb) - Sr - Ca - Cu - O superconducting tapes

Zhou¹,

Hong²,

Fei³

1996

“…It is quite dangerous to compare different compounds, which have not the same manufacturing process. Nevertheless, Oata et al [35] reported a higher anisotropy for a BSCCO-2212 sample than a BSCCO-2223 sample, both being screen-printed tapes. The sharper curves for the BSCCO-2212 compound than for the BSCCO-2223 sample in our measurement (figures 2 and 8) bring us to the same conclusion.…”

Section: Discussionmentioning

confidence: 98%

Angular effects of transport critical currents in high-temperature superconductor tapes

Warmont

Jones²

2001

Measurements of the critical current dependence on the angular orientation of the applied magnetic field for (Bi, Pb)2Sr2Ca2Cu3O10 (BSCCO-2223)/AgMg-sheathed, mono-core BSCCO-2223/Ag-sheathed and Bi2Sr2CaCu2O8 (BSCCO-2212) dip coat tapes are presented. We have demonstrated that the procedure of measurement is an important factor for the angular effect to show. For a magnetic field only applied during the measurement of Ic(θ) (during the rotation the magnetic field is set to zero) we have found a symmetric curve, while when the magnetic field is applied during the rotation the curve is asymmetric. Moreover, we found a large difference in the critical current value between the different procedures. From our measurements, we imply two conditions are necessary to have an angular effect: (1) the magnetic field must be applied during the rotation and (2) we have to start the rotation for a magnetic field parallel to the c-axis. The results are discussed in the context of the accommodation of vortices to planar defects and surface pinning.

“…High quality superconductors can be achieved by a combination of partial melting and slow solidification processes for Bi-2212 coated tapes. This method allows for a well aligned microstructure with high critical current density (J c ) [1,3,4]. Depending on the further application of these tapes, two basic techniques are established for tape production known as 'react-and-wind' [1,2,5,6] and 'wind-and-react' [7][8][9][10] techniques.…”

Section: Introductionmentioning

confidence: 99%

Superconducting joints of Bi-2212/Ag tapes and laminates

Ilyushechkin

Yamashita

Talbot

2000

Different types of HTS joints of Bi-2212/Ag tapes and laminates, which are fabricated by dip-coating and partial-melt processes, have been investigated. All joints are prepared using green single and laminated tapes and according to the scheme: coating-joining-processing. The heat treated tapes have critical current (I c ) between 7 and 27 A, depending on tape thickness and the number of Bi-2212 ceramic layers in laminated tapes. It is found that the current transport properties of joints depend on the type of laminate, joint configuration and joint treatment. I c losses in joints of Bi-2212 tapes and laminates are attributed to defects in their structure, such as pores, secondary phases and misalignment of Bi-2212 grains near the Ag edges. By optimizing joint configuration, current transmission up to 100% is achieved for both single tapes and laminated tapes.