Thallium barium calcium copper oxide

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Schematic layered structure of TBCCO-2223.

Thallium barium calcium copper oxide, or TBCCO (pronounced "tibco"), is a family of

high-temperature superconductors having the generalized chemical formula TlmBa2Can−1CunO
2n+m+2.

Tl2Ba2Ca2Cu3O10 (TBCCO-2223) was discovered in Prof. Allen M. Hermann's laboratory in the physics department of the

Paul Chu
in February 1988.

The first series of the Tl-based superconductor containing one Tl–O layer has the general formula TlBa2Can-1CunO2n+3,[2] whereas the second series containing two Tl–O layers has a formula of Tl2Ba2Can-1CunO2n+4 with n =1, 2 and 3. In the structure of Tl2Ba2CuO6 (Tl-2201), there is one CuO2 layer with the stacking sequence (Tl–O) (Tl–O) (Ba–O) (Cu–O) (Ba–O) (Tl–O) (Tl–O). In Tl2Ba2CaCu2O8 (Tl-2212), there are two Cu–O layers with a Ca layer in between. Similar to the Tl2Ba2CuO6 structure, Tl–O layers are present outside the Ba–O layers. In Tl2Ba2Ca2Cu3O10 (Tl-2223), there are three CuO2 layers enclosing Ca layers between each of these. In Tl-based superconductors, Tc is found to increase with the increase in CuO2 layers. However, the value of Tc decreases after four CuO2 layers in TlBa2Can-1CunO2n+3, and in the Tl2Ba2Can-1CunO2n+4 compound, it decreases after three CuO2 layers.[3]

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