Block-Layer Concept for the Layered Co Oxide: A Design for   Thermoelectric Oxides
  High-Tc Cu oxides consist of the alternating stack of the superconductive CuO2 layer and the block layer, such as Bi2Sr2O4 or La2-xSrxO2. By changing the block layer, we can change their physical properties, such as transition temperature Tc. The thermoelectric Co oxides have a similar layered structure composed of the conductive CoO2 layer and the blocking layer. Thus, we propose that their thremoelectric properties can be finely tuned by modifying the block layer. 
Takenori Fujii and Ichiro Terasaki