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Thin films of high Tc cuprate superconductors have been prepared by spinning on metal organic precursors from solution, followed by pyrolysis to oxide films. This new technique allows easy manipulation of film stoichiometry, and gives excellent compositional uniformity throughout the films. A 1600 A film of Ba2YCu3O7 on 〈100〉 MgO had a room temperature resistivity of 500 μΩcm, Tc(onset) of 90K, and R=0 at 58K. The film morphology was essentially a single planar array of grains with lateral dimensions of 2–5μm, oriented with the orthorhombic c axis perpendicular to the substrate. The preparation and electrical and microstructural characterization of thin films of Ba2YCu3O7 and other high Tc cuprates will be discussed.

A key requirement for many practical applications of the new class of high Tc superconductors is the ability to sustain high current densities in the presence of magnetic fields. The new materials present two substantially different behaviors. For Ba2YCu3O7 critical current behavior of polycrystalline material is dominated by intergranular transport. We will review a model for transport involving the effects of the correlation of defects with grain boundary orientation, the presence of impurities at the grain boundaries, measurements of tunneling characteristics through boundaries, and the effect of grain alignment on critical current. The case is substantially different in the 84 K superconducting phase Bi2.2Sr2Ca0.8Cu2O8+δ where there is a very strong dependence of critical current densities at 30–84 K on magnetic field for single crystals. There is a lack of threshold behavior in the I‐V characteristics in finite applied fields larger than Hc1(T) which is attributable to flux motion. This suggests that...

Laser induced etching has been used to pattern 2000–7000 A thick films of the superconducting perovskite Ba2YCu3O7 and its amorphous precursor. A 5145 A Ar+ laser beam, focused to a 1.0 μm beam diameter, with incident intensities of 5–250 mW, scanned at rates of 20–200 μm/s in air locally heated the optically absorbing films to induce reaction. Local melting was observed during the laser scans, indicating temperatures in excess of 950°C induced in predominantly perovskite phase films. Ablated grooves 1.5–3.0 μm wide were generated, with destruction of the superconducting phase verified by optical microscopy over a wide range of laser parameters. Scanning Auger and energy dispersive x‐ray analyses were used to monitor local chemical composition near the cuts. A wide range of behavior was found for etching of the amorphous precursor films, ranging from simple ablation, to multiple phase segregation, to generation of periodic morphological structure characteristic of local plasma formation in the ejected plu...