MODULATED STRUCTURE OF THE HIGH-TC SUPERCONDUCTOR BI2-XPBXSR2CACU2OY

Modulated structures in the Pb-doped Bi-Sr-Ca-Cu-O superconducting oxides, Bi2-xPbxSr2Ca-Cu2Oy (chi = 0 approximately 0.8), were studied by means of high resolution electron microscopy and electron diffraction. Two types of modulated structure with different modulation modes and cell dimensions were found in the compound. The Pb content was closely related to the structure types and the periods of modulation. Intensity distributions of superstructure reflections were analyzed by taking atomic displacive modulation into consideration. The changes of modulation mode and period were discussed in relation to the lattice parameter change with the Pb content.