MICROWAVE SURFACE-RESISTANCE OF BI2SR2CACU2OX THICK-FILMS ON LARGE-AREA METALLIC SUBSTRATES

As a feasibility study for application of a high-T-c material to an ac celerator cavity, Bi2Sr2CaCu2Ox thick films were formed on large-area metallic substrates. The microwave surface resistance of the films was measured over a temperature range from 4.2 K to 300 K using a demount able cylindrical copper cavity operated at 3 GHz in the TE011 mode. Th e area of the end plate was 177 cm(2) and the thickness of the films w as around 50 mu m. The films were formed either on silver foils (on co pper) or on a silver plate, coated by either a screen-printing or a sp ray-coating method, sintered either in air or in a Bi2O3 atmosphere, b oth at 885-890 degrees C, and either annealed in nitrogen gas at 600 d egrees C or not annealed. The ratio of the microwave surface resistanc e of the best film to that of the copper was 0.18 at 10 K and 0.05 at 77.3 K. A comparison of the microwave surface resistance is made betwe en Bi2Sr2CaCu2Ox and YBa2Cu3O7-x films.