Synthesis of Bi2Sr2CanCun+1Ox Films by Multilayer Deposition Technique

Soon after the discovery of high Tc superconductors in Bi-Sr-Ca-Cu -O systemsl, i.e., 80 K and 110 K phases, it was realized that the 110 K mono phase was extremely difficult to be synthesized by the conventional solid state reaction. Frequent intergrowth of many phases, i.e. Bi2Sr2CanCun+1Ox (n=0–6) are observed2. This suggests that the free energy of these phases has no sharp minimum against the number of CaCu layers sandwitched with two neighboring Bi2O2 layers. The sequential deposition technique is one of the most promising methods to obtain non equilibrium or metastable material having layered structure. We have attempted to synthesize the phases with n=0,1,2 or 3. In this paper we shall report on our sequential vapor deposition technique, characterization of the resultant multilayered films by X-ray diffraction and by SEM and finally their superconducting transion.