The crystal structures of the known superconducting copper oxides can be described in terms of two basic structural types. The series La2Can-1CunO2n+2, (Tl,Bi)2(Ba,Sr)2Can-1CunO2n+4 and TlBa 2Can-1CunO2n+3 can be viewed as made of alternating slices having the rock salt and perovskite structure. The compounds Ba2YCu4O8 and Ba4Y2Cu7O14+x, on the other hand, comprise of perovskite blocks alternating with blocks in which a crystallographic shear is present. The effect of this shear is that of forming double chains of edge sharing squares with oxygen atoms at the corners and copper atoms at the center. The superconductor Ba2YCu3O7 can be described in terms of both structural types and may be considered as an intermediate type between the other two. The basic building blocks of these superconducting materials can be further broken down into constituent nets (or meshes). This description allows one to envisage new structures built from these meshes containing the key structural elements present in the currently known superconductors. As such, the structural schemes used in this description may be used as a guide in the preparation of new materials with interesting electronic properties.
All Science Journal Classification (ASJC) codes
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering