Spin-on Bi4Sr3Ca3Cu4O16+x superconducting thin films from citrate precursors

Publisher Website
Google Scholar
Abstract
Thin films in the Bi‐Sr‐Ca‐Cu‐O system have been synthesized from homogeneous liquid citrate precursors by a spin‐coating and pyrolysis method. Films prepared on SrTiO3 substrates of [100] orientation show strongly textured orientations with the c axis of the predominant Bi4 Sr3 Ca3 Cu4 O16+x phase normal to the film plane. In a single coating and firing, crack‐free films of 0.2–0.5 μm thickness are obtained. For films fired to peak temperatures of 850–875 °C, linearly decreasing resistance with temperature is observed, with ρ (300 K)∼460 μΩ cm and ρ (300 K)/ρ (100 K)∼2.4. Clear onsets of superconductivity are observed at 90–100 K, with occasional films showing smaller resistant drops at 110–120 K. For all films, Tc (R=0) occurs in the range 70–75 K. High critical current densities at 4.2 K of 5–8×105 A/cm2 are measured by direct transport.