Terraced surfaces of Bi-Co complex oxide, (Bi, Pb)2Sr2CoOy, are examined by means of high-resolution transmission electron microscope (HRTEM) profile imaging method. The outermost surface of each step is a single (BiO) layer, which preserves wavy fluctuations of atom-plane almost in the same manner as those in the bulk-modulation. Some of (BiO)-layers near the edge of the crystal are not double but single (BiO) layers. In addition, an extremely small crystal of Bi2 (Sr, Ca)3Cu2Oy with unit-cell-size width is found to have the modulated structure almost identical with the bulk-modulation.
