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The unit cell of BSCCO-2212. The other BSCCO family members have very similar structures: 2201 has one less CuO2 in its top and bottom half and no Ca layer, while 2223 has an extra CuO2 and Ca layer in each half.

Bismuth strontium calcium copper oxide, or BSCCO (pronounced "bisko"), is a family of high-temperature superconductors having the generalized chemical formula Bi2Sr2CanCun+1O2n+6-d, with n=1 being the most commonly-studied compound (though n=0 and n=2 have also received significant attention). Discovered in 1988 by a Japanese group,[1] BSCCO was the first high-temperature superconductor which did not contain a rare earth element. It is a cuprate superconductor, an important category of high-temperature superconductors sharing a two-dimensional layered (perovskite) structure (see figure at right) with superconductivity taking place in a copper oxide plane. BSCCO and YBCO are the most studied cuprate superconductors.

Specific types of BSCCO are usually referred to using the sequence of the numbers of the metallic ions. Thus BSCCO-2212 (Bi2Sr2Ca1Cu2O8) has a critical temperature of 95 K and BSCCO-2223 (Bi2Sr2Ca2Cu3O10) has Tc = 108 K.[1] Both these critical temperatures are above the boiling point of liquid nitrogen, 77 K. These names are often abbreviated: for example, BSCCO-2212 is usually referred to as Bi-2212 or simply Bi2212.

BSCCO needs to be hole doped by cation substitution (e.g. Pb for Bi) or an excess of oxygen atoms in order to superconduct. This is usually done by adding interstitial oxygen atoms to the copper oxide plane. Tc is sensitive to the exact doping level: the max Tc for Bi-2212 is achieved with an excess of about 0.16 holes per Cu atom.[2] Tc is also sensitive to the duration of the sintering process.[3]

BSCCO is a Type II superconductor. The upper critical field in BSCCO polycrystalline samples at 4.2 K has been measured as 200±25 T (compare with 168±26 T for YBCO polycrystalline samples at 4.2 K).[4]

Contents

Wires and tapes

For practical applications, BSCCO is compressed with silver metal into tape via the PIT process
A piece of Bi2223. (The two lines in the background are 1 mm apart.)

Bi2212 was the first high-temperature superconductor to be used for making superconducting wires. Although it has the same problems with weak links at crystal grain boundaries as YBCO, for BSCCO this can be overcome by a texture evolution during the rolling process due to Van-der-Waals coupled BiO layers, which are not present in YBCO. However, its critical current density (maximal Amps per square Metre of cross-sectional area) in magnetic fields at elevated temperatures is ~480 A/cm2, about a factor 10 less than that of YBCO.[5]

Both Bi2212 and Bi2223 can be made into wires via the Powder-in-tube process, though Bi2223 then has to be rolled into a tape to align the crystals sufficiently to form a useful superconductor. [6][7]

Applications

References

  1. ^ a b H. Maeda, Y. Tanaka, M. Fukutumi, and T. Asano (1988). "A New High-Tc Oxide Superconductor without a Rare Earth Element". Jpn. J. Appl. Phys. 27 (2): L209-L210. doi:10.1143/JJAP.27.L209.  
  2. ^ S. M. Green et al. (1989). "Effects of compositional variations on the properties of superconducting (Bi,Pb)2Sr2Ca2Cu3Oδ". Journal of Applied Physics 66: 728–734. doi:10.1063/1.343546.  
  3. ^ H. K. Lee et al. (1989). "Preparation and properties of Pb-doped Bi-Sr-Ca-Cu-O superconductors". Journal of Applied Physics 66: 1881–1883. doi:10.1063/1.344370.  
  4. ^ A. I. Golovashkin et al. (1991). "Low temperature direct measurements of Hc2 in HTSC using megagauss magnetic fields". Physica C: Superconductivity 185-189: 1859. doi:10.1016/0921-4534(91)91055-9.  
  5. ^ K. Togano et al. (1988). "Properties of Pb-doped Bi-Sr-Ca-Cu-O superconductors". Applied Physics Letters 53 (14): 1329–1331. doi:10.1063/1.100452.  
  6. ^ C.L. Briant, E.L. Hall, K.W. Lay, I.E. Tkaczyk (1994). "Microstructural evolution of the BSCCO-2223 during powder-in-tube processing". J. Mater. Res. 9 (11): 2789–2808. doi:10.1557/JMR.1994.2789.  
  7. ^ Timothy P. Beales, Jo Jutson, Luc Le Lay and Michelé Mölgg (1997). "Comparison of the powder-in-tube processing properties of two (Bi2-xPbx)Sr2Ca2Cu3O 10+δpowders". J. Mater. Chem. 7: 653–659. doi:10.1039/a606896k.  

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Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

English

Initialism

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BSCCO

  1. bismuth, strontium, calcium, copper and oxygen, the composite elements in the manufacture of one type of high-temperature superconducting material
    • 2006. Graham P. Collins. "The Next Generation". Scientific American, 295(3): 22.
      "BSCCO wires are typically made by putting a powder inside a tube of silver that is then heated and drawn out."

References


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