<page_title> High-temperature superconductivity </page_title> <section_title> Bi-, Tl- and Hg-based high-Tc superconductors </section_title> <table> <cell> Tl2Ba2CaCu2O8 <col_header> Formula </col_header> </cell> <cell> Tl-2212 <col_header> Notation </col_header> </cell> <cell> 2 <col_header> No. of Cu-O planes in unit cell </col_header> </cell> </table>
In Tl₂Ba₂CaCu₂O₈ (Tl-2212), there are two Cu–O with a Ca layer in between.