Bismuth strontium calcium copper oxide

Bismuth strontium calcium copper oxide

Bismuth strontium calcium copper oxide, or BSCCO (pronounced "bisko"), is a family of high-temperature superconductors having the generalized chemical formula Bi2Sr2Ca"n"Cu"n"+1O2"n"+6-d.

BSCCO was also the first high-temperature superconductor to be discovered which did not contain a rare earth element.

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" = 107 K. Both these critical temperatures are above the temperature of liquid nitrogen (b.p. 77 K).

BSCCO-2212 (and probably -2223) need to be hole doped by cation substitution (eg Pb for Bi) or an excess of oxygen atoms in order to superconduct. "Tc" is sensitive to the exact doping level. The max "Tc" for BSCCO-2212 is achieved with an excess of about 0.16 holes per Cu.

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 (Contrast with 168±26 T for YBCO polycrystalline samples at 4.2 K) [http://cat.inist.fr/?aModele=afficheN&cpsidt=5183174 Abstract] .

Wires and tapes

BSCCO-2212 is the first high-temperature superconductor to be used for making conducting 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 about a factor 10 less than that of YBCO.

Both BSCCO-2212 and BSCCO-2223 can be made into wires via the Powder-in-tube process, though BSCCO-2223 then has to be rolled into a tape to align the crystals sufficiently to form a useful superconductor [http://www.mrs.org/s_mrs/sec_subscribe.asp?CID=3168&DID=185813&action=detail] [http://www.rsc.org/ej/JM/1997/a606896k.pdf (Bi,Pb)SCCO-2223 PIT ] .

History

Discovered in 1988 by US and Japanese groups.Japanese : H. Maeda, Y. Tanaka, M. Fukutumi, and T. Asano, Jpn. J. Appl. Phys. 27, L209(1988).

Applications

* [http://at-mel-cf.web.cern.ch/at-mel-cf/html/HTS_materials.htm Testing BSCCO tapes at CERN ]
* [http://www.sei.co.jp/news_e/press/07/07_09.html Sumitomo Electric SC motor ]

References

External links

* [http://www.magnet.fsu.edu/magnettechnology/research/asc/research/bscco.html BSCCO-2223 tape at US Lab ]

* [http://psroc.phys.ntu.edu.tw/cjp/download.php?d=1&pid=995 Research fabrication of 2212 on MgO in 1993 ] (pdf)

* [http://www.sei.co.jp/super/hts_e/index.html Sumitomo Electric offering BSCCO-2223 ] Includes data and images.

* [http://users.physik.fu-berlin.de/~vonoppen/papers/prl_96_197002.pdf Local Electronic Structure of Bi2Sr2CaCu2O8 near Oxygen Dopants ... ]

* [http://arxiv.org/abs/cond-mat/0507106v1 The change of Fermi surface topology in BiSrCaCuO-2212 with doping. ]


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