Superconductors.ORG herein reports synthesis of the first 200K superconductor in conjunction with the discovery of a new superconductor system.

The 200K material is believed to have a B212/1212C intergrowth structure, where B=11 and C=copper chain. This structure is shown below left and has the chemical formula Sn₆Ba₄Ca₂Cu₁₀O_y. The general formula for this new family of superconductors is Sn_xBa₄Ca₂Cu_(x+4)O_y. Within this new family, unit cells with 3 to 6 atoms of tin (x) have been found to superconduct, with 6 atoms of tin producing a new record high Tc near 201K.
This intergrowth is highly lopsided, as was the Sn-In-Pb-Tm cuprate that produced a 195K superconductor in July 2008. However, it achieves its very high transition temperature through application of planar weight disparity (PWD) in the insulating layers, instead of the CuO2 planes.
Above is a composite magnetization test, showing the Meissner transition occuring just above 202K. A flashing line has been added to illustrate the diamagnetic shift in slope below Tc. The quiescent noise is a result of zooming in on a small volume fraction.

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