摘要
It is one of the important ways that the foreign elements can be used as a probe to be substituted into the lattice so as to obtain the information about the electronic and crystal structure of the cuprate oxide superconductors. Obviously, it is essential to determining the real substituted site by foreign elements in discussion of the substitution effect. It is known that the positron annihilation technique (PAT) is highly sensitive to the changes in electronic and defect structure of the materials. Since Jean et al. reported
