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Bismuth strontium calcium copper oxide, or BSCCO (pronounced "bisko"), is a family of high-temperature superconductors having the generalized chemical formula Bi2Sr2Ca''n''-1Cu''n''O2''n''+4+x, with ''n''=2 being the most commonly studied compound (though ''n''=1 and ''n''=3 have also received significant attention). Discovered as a general class in 1988,〔 〕 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 Bi-2201 is the ''n''=1 compound (Bi2Sr2CuO6+x), Bi-2212 is the ''n''=2 compound (Bi2Sr2CaCu2O8+x) and Bi-2223 is the ''n''=3 compound (Bi2Sr2Ca2Cu3O10+x). The BSCCO family is analogous to a thallium family of high-temperature superconductors referred to as TBCCO and having the general formula Tl2Ba2Ca''n''-1Cu''n''O2''n''+4+x, and a mercury family HBCCO of formula HgBa2Ca''n''-1Cu''n''O2''n''+2+x. There are a number of other variants of these superconducting families. In general their critical temperature at which they become superconducting rises for the first few members then falls. Thus Bi-2201 has Tc ≈ 2 K, Bi-2212 has Tc ≈ 95 K, Bi-2223 has Tc ≈ 108 K, and Bi-2234 has Tc ≈ 104 K. This last member is very difficult to synthesize. ==Discovery== BSCCO as a new class of superconductor was discovered around 1988 by Hiroshi Maeda and colleagues〔 at the National Research Institute for Metals in Japan, though at the time they were unable to determine its precise composition and structure. Almost immediately several groups, and most notably Subramanian ''et al'' at Dupont and Cava ''et al'' at AT&T Bell Labs, identified Bi-2212. The ''n''=3 member proved quite elusive and was not identified until a month or so later by Tallon ''et al'' in a government research lab in New Zealand. There have been only minor improvements to these materials since. A key early development was to replace about 15% of the Bi by Pb, which greatly accelerated the formation and quality of Bi-2223. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Bismuth strontium calcium copper oxide」の詳細全文を読む スポンサード リンク
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