In early 1988, a new class of superconductor was discovered with unusually high TC values. Upto 1986, the highest TC value observed in the superconducting material is 23K. In 1986 superconducting cuprate discovered by Bednorz and Muller with TC value 30K, has the formula La2-xBaxCuO4. By 1987, materials discovered with TC value 93K and it rise to 125 K in 1988.The rapid increase in TC has led to the hope that it might be possible to develop materials that are superconductors at room temperature. Such materials could enable the transmission of electric power over long distances without resistive losses.
The high TC superconductors are oxides of copper in combination with other elements, They are ceramics, which means that they are brittle and hardly formed into wires to carry current. The crystal structure is characterized by planes of copper and oxygen between planes of the other element. The structure of orthorhombic YBa2CuO7 is given in Fig 22.
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