Elemental Substitution Effects in High-Tc Superconductor YBa2Cu3O7-δ*

This paper reports the experimental results of the investigation on elemental substitution effects in YBaCuOand the new physical ideas deduced comprehensively. It is shown that all the orthorhombic crystalline structure, oxygen content, oxidation valence of Cu atoms, and metal-semiconductor （insulator） transition are only the extrinsic factors deter mining the Tof the systems, and there are two mechanisms of substitution effects, namely the mechanism of the substitution effects outside the CuOplanes and that within the CuOplanes. We suggest that the mobile carrier concentration and the dynamic, short-range antiferromagnetic correlation between Cu（2） atoms on the CuOplanes are the two intrinsic factors determining the high Tsuperconductivity.