Crystal Chemistry of Superconducting Oxides and Related Phases

In the cuprate based superconductors and related phases, different building units of [CuO sub x] occur, forming planar squares (x=4), pyramids (x=5) and octahedrons (x=6), as well as the linear O-Cu-O arrangement (x=2). These units can be connected in different ways, resulting in a wealth of different possible structures. 

Various arrangements that are found in superconductors and their relation to other phases will be discussed. Key structural element is the Cu-O bond distance (usually around 1.92angstroms which determines the metric of the unit cells.