Abstract:
The TlCa1−x Lnx Sr2 Cu2 O7+δ(Ln = rare earth) system shows electron-superconductivity when x= 0.25 and hole-superconductivity when x > 0.25. The Tc is generally in the 60–90K in both these regimes. TlSr2−x Lax CuOy (1021) also show electron or hole superconductivity (Tcn∼40K) depending on x.
