Using Bi-based oxide superconductors of the Bi0.96Pb0.24-xSbxSr1.0Ca 1.1 Cu1.6Oy composition which were prepared by the sol-gel method, production of the high-Tc phase and also microstructures of the high-Tc and the low-Tc phases were investigated using the XRD method and the TEM technique. Two superconducting phases showed good linearities of shrinkages of the a, b, and c lattice parameters as the Sb content increased, and so it has been found that Sb can be included in superconducting crystal structures. However, all shrinkages were below 1%. The activation energy of Sb diffusion was estimated from time dependence of changes of the lattice parameters using the Arrhenius plots. Its energy was from 510 to 593 Kj/mol.