Structural phase transition and diamagnetism at 36K IN La2CuO4

Both, La 2 CuO 4 and La 1·85 ,Sr 0.15 CUO 4 exhibit a bulk phase transition around 36K in the thermal expansion. While in La 1.85 Sr 0.15 CuO 4 this is associated with bulk superconductivity, demonstrated by a Meissner effect of ∼ 13%, the superconducting volume fraction of La 2 CuO 4 amounts to only 10 −4 of the total volume. In La 2 CuO 4 time-dependent phenomena were observed.