Doping structure of the high temperature superconductor La2-ΔCa1+ΔCu2O6+δLa2-ΔCa1+ΔCu2O6+δ

The double doped unit cell of La2-ΔCa1+ΔCu2O6+δLa2-ΔCa1+ΔCu2O6+δ (LCCO-52) consists of two chemical formulas, La2CaCu2O7 and Ca3Cu2O6 which are responsible for the occurrence of superconductivity with n=2 superconducting CuO2 planes per chemical formula. The distance x between double doped unit cells projected into a CuO2 plane matches the experimental transition temperature Tc quite well.