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

high-temperature superconductor High-temperature superconductivity (high-c or HTS) is superconductivity in materials with a critical temperature (the temperature below which the material behaves as a superconductor) above , the boiling point of liquid nitrogen. They are "high- ...

s having the generalized

chemical formula A chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, such as pare ...

Tl_''m'' Ba₂ Ca_''n''−1 Cu_''n'' O_{2''n''+''m''+2}. Tl₂Ba₂Ca₂Cu₃O₁₀ (TBCCO-2223) was discovered in Prof. Allen M. Hermann's laboratory in the physics department of the

University of Arkansas The University of Arkansas (U of A, UArk, or UA) is a Public university, public Land-grant university, land-grant research university in Fayetteville, Arkansas, United States. It is the Flagship campus, flagship campus of the University of Arkan ...

in October 1987 by the post-doctoral researcher Zhengzhi Sheng and Prof. Hermann. The bulk superconductivity in this material was confirmed by observations of magnetic flux expulsion and flux trapping signals (under zero field cooled and field cooled conditions) with a SQUID

magnetometer A magnetometer is a device that measures magnetic field or magnetic dipole moment. Different types of magnetometers measure the direction, strength, or relative change of a magnetic field at a particular location. A compass is one such device, ...

in the superconductor laboratory of

Timir Datta Timir Datta is an Indian-American physicist specializing in high transition temperature superconductors and a professor of physics in the department of Physics and Astronomy at the University of South Carolina, in Columbia, South Carolina. Early ...

in the

University of South Carolina The University of South Carolina (USC, SC, or Carolina) is a Public university, public research university in Columbia, South Carolina, United States. Founded in 1801 as South Carolina College, It is the flagship of the University of South Car ...

. Allen Hermann announced his discovery and the

critical temperature Critical or Critically may refer to: *Critical, or critical but stable, medical states **Critical, or intensive care medicine *Critical juncture, a discontinuous change studied in the social sciences. *Critical Software, a company specializing in ...

of 127 K, in Houston, Texas at the World Congress on Superconductivity organized by Paul Chu in February 1988. The first series of the Tl-based superconductor containing one Tl–O layer has the general formula TlBa₂Ca_''n''−1Cu_''n''O_2''n''+3, whereas the second series containing two Tl–O layers has a formula of Tl₂Ba₂Ca_''n''−1Cu_''n''O_2''n''+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, ''T''_c is found to increase with the increase in CuO₂ layers. However, the value of ''T''_c decreases after four CuO₂ layers in TlBa₂Ca_''n''−1Cu_''n''O_2''n''+3, and in the Tl₂Ba₂Ca_''n''−1Cu_''n''O_2''n''+4 compound, it decreases after three CuO₂ layers.

References

*''Copper Oxide Superconductors:, by Charles P. Poole, Timir Datta, Horacio A. Farach, John Wiley & Sons, 1988, '' *''Superconductivity: Its historical Roots and Development from Mercury to the Ceramic Oxides, by Per Fridtjof Dahl, AIP, New York, 1st ed. 1992, ''

External links

Thallium-based high-temperature superconductors
{{Thallium compounds High-temperature superconductors Thallium compounds Barium compounds Calcium compounds Copper(II) compounds Oxides

See also

References

External links