Correlation between Tc, in-plane Cu-O-Cu bond length, and buckling of the CuO2 plane in cuprate superconductors

Correlation between transition temperature, in-plane copper-oxygen-copper b ond length and buckling of the CuO2 plane in optimally doped copper oxide s uperconductors was investigated. As for cuprates with double CuO2 layers, a ll the compounds had buckling type distortion in a CuO5 pyramid. The degree of distortion was determined only by a kind of cation between the two faci ng CuO5 pyramids, that is, calcium or yttrium. A higher transition temperat ure was obtained for a copper oxide with having larger Cu-O-Cu length and s maller buckling degree.