CHEMICAL VAPOR-DEPOSITION OF THE SUPERCONDUCTING PHASE IN THE BI-SR-CA-CU-O SYSTEM FROM DIFFERENT HALIDE PRECURSORS

Chemical vapour deposition (CVD) of the superconducting phase in the Bi-Sr-Ca-Cu-O system from the halide precursors BiX3, SrX2, CaX2 and CuX, where X = Cl or I, is thermodynamically investigated. The oxygen source was O2, H2O or a mixture of O2 + H2O. The effect of different deposition parameters on the yield of the binary oxides is studied for simultaneous deposition of the four binary oxides and the results are summarized in calculated CVD phase diagrams. The choice of metal halide is found to affect the size of the region where all four binary oxides can be deposited to a large extent. Iodides as metal precursors with either O2 or a mixture of H2O + O2 with a low [H2O] [O2] molar ratio as the oxygen source yield much larger stability regimes than chlorides. If chlorides are used as metal precursors, the presence of H2O is found to be necessary for simultaneous deposition of the four binary oxides. © 1990.