Cuprate high-temperature

CUPRATE HIGH-TEMPERATURE SUPERCONDUCTORS 8.6.1 Perovskite-Related Structures and Series... 

Fig. 27.5 (a) A unit cell of perovskite, CaTi03, using a polyhedral representation for the coordination environments of the Ti centres an O atom (red) lies at each vertex of the octahedra, and the Ca ion is shown in grey, (b) Part of a layer of stoichiometry Cu02 which forms a building block in all cuprate high-temperature superconductors colour code Cu, brown O, red. 

Cuprate high-temperature superconductors are copper-containing perovskite-derived oxides. Many of these maintain the superconducting state to temperatures above that of liquid nitrogen (Table 8.1). The stmctures of the superconductors are built up of slices of perovskite type linked by slabs with stmctures (in the main) of the rock salt (NaCl) or fluorite (CaFj) type (Section 4.6). The copper valence in most compounds lies between the formal values of Cu and Cu ". 

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