Strategies for tailoring new superconducting systems

Three different strategies for tailoring new superconducting systems and op timizing existing ones are reviewed. The first is based on band structure c alculations and the use of empirical criteria as suggested by LF Mattheiss for evaluating the capability of new materials to host superconductivity. B aBiO3 is illustrated as an example. The second is based on high resolution electron microscopy studies and deals with finding defects in existing syst ems, which could lead to new structural arrangements. The discovery of Hg2B a2(Y, Ca)Cu2O8-x is illustrated. The third strategy is based on the pressur e effect on T-c. This strategy implies that the subsequent structural studi es indicate the substitutions which might simulate the pressure effect. Thi s strategy has been successful only for the La2CuO4 system.