Abstract
Herein, we review the magnetic, superconducting and structural phase diagrams of the title systems, with an emphasis on our recent results form magnetic and structural neutron diffraction, magnetic susceptibility and system, and indicate the occurrence of frustrated phase separation on a nanoscopic length scale in the La
2-
x
Sr
x
CuO
4 system with O <
x ≲ 0.05.
139La nuclear quadrupole resonance measurements. The results clarify the miscibility gap in the La
2CuO
4+δ