High-pressure synthesis of homologous series of high critical temperature (Tc) superconductors

Under high pressure, a variety of elements can be accommodated at the cation sites in the charge reservoirs of cuprate superconductors. Furthermore, high pressure allows the insertion of higher number of CuO2 planes (i.e., the insertion period of a charge reservoir becomes variable). Because of these effects, many new high critical temperature (T-c) superconductors have been discovered under high pressure. In this paper, we will survey their structural and superconducting properties. The role of high pressure and its effect on the size mismatch between the charge reservoir and the CuO2 plane will also be discussed.