Advances in Bi-Based High-Tc Superconducting Tapes and Wires

MRS Bulletin ◽  
2001 ◽  
Vol 26 (2) ◽  
pp. 121-125 ◽  
Author(s):  
Hitoshi Kitaguchi ◽  
Hiroaki Kumakura
Keyword(s):  
Low Temperature ◽  
High Field ◽  
Superconducting Magnet ◽  
Oxide Superconductors ◽  
Critical Fields ◽  
High Tc ◽  
Practical Applications ◽  
High Transition ◽  
Promising Application ◽  
Upper Critical Fields

Since the discovery of high-Tc superconductors (HTSs), especially the Bi-based oxide superconductors (Bi-HTSs) in 1989, much effort has been concentrated on the fabrication of Bi-HTS wires and tapes. Bi-HTSs are interesting materials from the viewpoint of practical applications. One of the interesting applications of Bi-HTSs is the cryogen-free conduction-cooled magnet. Besides having a high transition tem- perature (Tc), Bi-HTSs have high upper critical fields (Bc2) or high irreversibility fields (Birr) at temperatures below ∼30 K. Because ∼30 K can be efficiently main- tained by a cryocooler, a Bi-HTS magnet cooled with a cryocooler has great potential in many technological applications. Another promising application of Bi-HTSs is the high-field magnet. When the temperature is reduced to ∼5 K, Bi-HTSs show a much higher Bc2 or Birr than do conventional metallic superconductors (low-temperature superconductors, LTSs) such as Nb3Sn. This indicates that Bi-HTSs also have great potential for use in a high- field superconducting magnet if the magnet is operated at low temperature.

UPPER CRITICAL FIELD OF HIGH Tc SUPERCONDUCTING OXIDES

1987 ◽  
Vol 01 (02) ◽  
pp. 451-453
Author(s):  
Changgeng CUI ◽  
Shuquan GUO ◽  
Shanlin LI ◽  
Lie CHEN ◽  
Cheng DONG ◽  
...  
Keyword(s):  
Least Squares ◽  
Critical Field ◽  
High Field ◽  
Upper Critical Field ◽  
Critical Fields ◽  
High Tc ◽  
Dirty Limit ◽  
Straight Line ◽  
Upper Critical Fields ◽  
Superconducting Oxides

Upper critical fields Bc2(T) near Tc have been measured for the samples of Ba2YCu3Ox and Ba2GdCu3Ox. The upper critical field slope (dBc2dT)Tc and the upper critical field Bc2(O) have been calculated by using the least squares filling of straight line and using WHH expression in dirty limit respectively. The results show that Bc2(O) can be reach 114T and 127T for the samples of Ba2YCu3Ox and Ba2GdCu3Ox respectively. It is observed that there is a upwards curvature near Tc in the curves of B(T) vs.T. The main reason might be a proximity type effect in which a small amount of high Tc materials is able to raise the effective Tc of the samples, However such an effect could be suppressed at high field.

Theories of High Tc Superconductors

1987 ◽  
Vol 99 ◽  
Author(s):  
John Bardeen
Keyword(s):  
Low Temperatures ◽  
Landau Theory ◽  
3D Models ◽  
Oxide Superconductors ◽  
High Tc Superconductors ◽  
Pairing Interaction ◽  
Ginzburg Landau ◽  
High Tc ◽  
Wide Range ◽  
High Transition

ABSTRACTMany theories have been given to account for the high transition temperatures in the oxide superconductors. While most are based on pairing, they differ as to the origin of the attractive interaction that gives rise to the pairs and whether the pairing is weak or strong. If weak(λ < ∼ 0.5), the energy range of the pairing interaction must be wider than is consistent with one mediated solely by phonons. With measurements on single crystals becoming available, giving data covering a wide range of frequencies and temperatures, it is possible to narrow down the possible options. The data show that anisotropie 3D models are required. Observed isotope shifts indicate that phonons must play a role, but additional mechanisms are likely necessary to account for the high T's. Thermal, magnetic and transport data are consistent with anisotropie Ginzburg-Landau theory near T, with expected departures at low temperatures.

Low Temperature Growth of High Tc Oxide Superconductors

1988 ◽  
Author(s):  
Yoshichika BANDO ◽  
Takahito TERASHIMA ◽  
Kenji IIJIMA ◽  
Kazunuki YAMAMOTO ◽  
Jun TAKADA ◽  
...  
Keyword(s):  
Low Temperature ◽  
Oxide Superconductors ◽  
High Tc ◽  
Temperature Growth ◽  
Low Temperature Growth

Identifying the Pairing Mechanism in High-Tc Superconductors

1989 ◽  
Vol 156 ◽  
Author(s):  
J.B. Goodenough ◽  
A. Manthiram ◽  
J. Zhou
Keyword(s):  
Stress Relief ◽  
Redox Couple ◽  
Oxide Superconductors ◽  
High Tc Superconductors ◽  
Pairing Mechanism ◽  
Strong Electron ◽  
High Tc ◽  
Two Factors ◽  
High Transition ◽  
Copper Oxide Superconductors

ABSTRACTIt is argued that the origin of the high transition temperatures observed in Ba1−xKxBiO3 and the copper-oxide superconductors with perovskite-related structures is due to two factors: (1) overlap of a partially filled σ* band of primarily cation character and a π or π* band of mostly O-2pπ parentage permits charge transfer between cation and anion subarrays with oxygen-atom displacement perpendicular to a M-O-M bond axis and (2) bondlength mismatch places the M-O-M bondlength under a compressive or tensile stress. Relief of a compressive stress by the bending of a M-O-M bond from 180° introduces a strong electron-lattice interaction with holes; a 180° Cu-O-Cu bond allows strong electronlattice coupling with electrons of a Cu2+/+ redox couple, but not with holes in a Cu3+/2+redox couple.

POSSIBLE MECHANISM OF PAIRING IN HIGH Tc SUPERCONDUCTORS: A MULTI-COMPONENT PLASMA MODEL

1988 ◽  
Vol 02 (05) ◽  
pp. 873-881
Author(s):  
J. Mahanty ◽  
M. P. Das
Keyword(s):  
Interaction Potential ◽  
Oxide Superconductors ◽  
Plasma Model ◽  
High Tc Superconductors ◽  
High Tc ◽  
Gap Equation ◽  
Ion Plasma ◽  
Electrons And Ions ◽  
Component Plasma ◽  
High Transition

Screening of a pair of point charges in a medium of electrons and ions is studied using the hydrodynamical model, treating the system as a multi-component plasma. When some of the ion plasma branches possess negative dispersion, the interaction potential of the pair can become attractive and large in certain regions of momentum space under certain conditions. By using this potential in the BCS gap equation, high transition temperatures have been obtained. Applicability of this model to oxide superconductors is discussed.

Upper Critical Fields of the High-Tc Superconductor YBa2Cu3O7-δ: Possibility of 350 T

1988 ◽  
Vol 146 (2) ◽  
pp. K103-K107 ◽  
Author(s):  
K. Rogacki ◽  
C. Sułkowski ◽  
A. J. Zaleski ◽  
Z. Bukowski ◽  
B. Greń ◽  
...  
Keyword(s):  
Critical Fields ◽  
High Tc ◽  
High Tc Superconductor ◽  
Upper Critical Fields

INTRINSIC FLUX PINNING FORCE IN HIGH Tc OXIDE SUPERCONDUCTORS

1990 ◽  
Vol 04 (19) ◽  
pp. 1227-1236 ◽  
Author(s):  
Z.S. CAO ◽  
Y. ZHANG ◽  
Z.X. ZHAO
Keyword(s):  
Flux Pinning ◽  
Layer Structure ◽  
Oxide Superconductors ◽  
Pinning Force ◽  
High Tc ◽  
Pinning Centers ◽  
Intrinsic Flux ◽  
High Transition ◽  
Temperature Oxide ◽  
Flux Pinning Force

A phenomenological model concerning the intrinsic flux pinning in high transition temperature oxide superconductors was proposed. The coherence length of this type of superconductors is sufficiently short to enable the layer structure along the c-axis in crystal specimens to provide by itself the flux pinning centers which have the considerably large flux pinning force. The critical current density estimated from this mechanism is also large.

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