Perovskite oxides and high-temperature superconductivity

Electronic properties of oxide perovskites are briefly presented with special reference to quasi two-dimensional oxides of K2NiF4 structure. Structure and properties of the various families of cuprate superconductors containing perovskite layers are discussed in some detail, primarily based on the work carried out in the author's laboratory. The nature of Cu and oxygen in the cuprates is examined and the role of oxygen holes indicated. Oxygen holes seem to be present in many other perovskite oxides as well. The recently discovered electron-superconductivity in cuprates is presented as also the unusual dielectric properties of bismuth cuprate glasses. Scope for further investigations and possible future directions are indicated.