Superconductors BSCCO

Figure 2.20. Comparison of the crystal structures of Ocft-right) LSCO, YBCO, and BSCCO superconductors, respectively. Reproduced with permission from Prof. Hoffman s webpage at Harvard University http //hoffman.physics.harvard.edu/research/SCmaterials.php...

Why is the BSCCO superconductor the material of choice for superconducting wires ... 

In 1996, a 50 m underground superconducting cable (wound from 6 km of a BSCCO ribbon) and a 150 kW superconducting electric motor were successfully demonstrated. Further development of practical superconductor devices might well depend more on the development of suitable refrigeration technology than on the preparation of new superconducting materials. 

Here directions z and x correspond to the orientation of electric field across and along the layers correspondingly, Exz is the DC components of electric field, index (0 is related to the AC electric field components associated with the motion of JVL. In earlier calculations of dissipation in JFF regime [19, 24] only two first terms of Eq. (6) have been taken into account. However, as that has been pointed out recently [23], the third term can have the leading contribution for the highly anisotropic layered superconductors, satisfying the condition T = ( 1. For materials like BSCCO at low... 

Superconducting BSCCO films were produced in situ on 3" diameter sapphire substrates by plasma-enhanced halide LPCVD [266, 267]. Films consisting mainly of the Bi-2212 phase were deposited with metal halide precursors at 580°C under 0.1 Torr system pressure in the presence of a rf plasma. These films became superconducting at 70 K with = 2.5 x 10 Acm at 10 K. Plasma-enhanced halide LPCVD was also used to grow Bi-Sr-Ca-Cu-O/Bi-Sr-Cu-O superconductor-normal metal (S-N) heterostructures [259], HRTEM images showed the S/N interface to be atomically abrupt while variable temperature resistivity measurements gave T. = 75 K for the S/N heterostructure. 

New ceramic technologies have been developed for the preparation of thin-film superconductors YBa2Cu307-x (YBGO) on a monocrystalline SrTiOj substrate, as well as superconductor powders by Pb-doped Bi2Sr2Ga30io + Y (BSCCO) as a top-quality material (Binder and Gunther 1999). 

Most electronic applications are based on the turmel effect between two superconductors that are separated by a weak (isolating) link that is only a few atomic layers thick. Currently, Nb and A1 are used preferably to build Josephson tunnel junctions (JTJs), whereas ceramic superconductors are stiU less common. However, the situation may soon change following the discovery of coherently emitting tera-Hertz radiation of intrinsic BSCCO JTJs (Ozyuzer et al., 2007). Some aspects of electronic applications are considered in detail at this point. 

Shown in fig. 16 is the magnetic field dependence of the critical current density for the IBAD and RABiTS based YBCO coated samples recently produced at LANL and ORNL, respectively. These coated samples operated in the liquid nitrogen temperature range clearly outperform the metallic superconductors (NbTi, NbjSn) at 4.2 K. Furthermore, even in the worst field direction H c), and for temperatures below 65 K, the short sample YBCO coated conductors operated in a 8-tesla background field have at least an order of magnitude higher Jc than pre-commercial BSCCO-2223 wire with no applied field. 

Superconducting wires were first made from Bi2Sr2CaCu20g, known as BSCCO-2212, a high-temperature superconductor with r<. = 95 K. It can be prepared in wire forms because it has layers of bismuth and oxygen atoms that YBCO does not have. BSCCO-2212 is so named because its formula consists of two bismuth, two strontium, one calcium, and two copper atoms. Other BSCCO compounds exist too, and they all have a general formula of Bi2Sr2Ca,Cu + 02 +6. BSCCO-2223, for example, which has the formula Bi2Sr2Ca2Cu30,o (where n = 2), is a superconductor with Tc= 107 K. 

IC -Advanced Superconductors manufactures superconductive wire, cable, and tape for MRI diagnostic systems, high-energy physics, and fusion power research. Products are based on NbTi, NbjSn, BSCCO (Bi-Sr-Ca-Cu-O) 2212/Ag, and BSCCO 2223/Ag multi-fUament wire and tape. 

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