High-temperature superconductivity Bi-, Tl- and Hg-based high-  c  superconductors Critical temperature (T c ), crystal structure and lattice constants of some high-T c superconductors

| Formula | Notation | T_c_K | No_of_Cu_O_planes_in_unit_cell | Crystal_structure |
|---|---|---|---|---|
| YBa 2 Cu 3 O 7 | 123 | 92 | 2 | Orthorhombic |
| Bi 2 Sr 2 CuO 6 | Bi-2201 | 20 | 1 | Tetragonal |
| Bi 2 Sr 2 CaCu 2 O 8 | Bi-2212 | 85 | 2 | Tetragonal |
| Bi 2 Sr 2 Ca 2 Cu 3 O 6 | Bi-2223 | 110 | 3 | Tetragonal |
| Tl 2 Ba 2 CuO 6 | Tl-2201 | 80 | 1 | Tetragonal |
| Tl 2 Ba 2 CaCu 2 O 8 | Tl-2212 | 108 | 2 | Tetragonal |
| Tl 2 Ba 2 Ca 2 Cu 3 O 10 | Tl-2223 | 125 | 3 | Tetragonal |
| TlBa 2 Ca 3 Cu 4 O 11 | Tl-1234 | 122 | 4 | Tetragonal |