Hexagonal doping pattern in high temperature superconducting La2CuO4+δ formed by regular triangles

An orthorhombic crystal at superconducting temperatures and two different doping positions for the excess O-atom within a unit cell are responsible for a regular triangle doping structure within the CuO2 plane. The smallest possible hexagonal structure determines the highest doping density and the resulting doping distance x shows a strong correlation to Tc.