Low cost synthesis of high-Tc superconducting films on metallic substrates via ultrasonic spray pyrolysis Original Research Article

Ultrasonic spray pyrolysis technique has been used to deposit both in situ and ex situ high temperature superconducting films (HTSC) of Y1Ba2Cu3Ox(YBCO) and Bi2Sr2CaCu2Ox (BSCCO) compounds over various substrates. Nitrate precursor solutions are used to deposit films of ∼10 μm thickness. Both low temperature spray with substrate temperature Ts < 500 °C and high temperature deposition with Ts = 550–900 °C are carried out. Superconducting properties of these films are observed to vary with various parameters such as concentration of spray solution, deposition temperature and nature of substrate and annealing process. Best quality films show Tc (R = 0) of 89 K and Jc of ∼4 × 104 A/cm2 at 77 K and ∼ 105 A/cm2 at 20 K. X-ray diffraction pattern reveals that the films are textured along c-axis. Successful attempt has been made to deposit in situ superconducting films over polycrystalline Ag for coated conductor applications. Various deposition and annealing conditions are optimized to control the diffusion of Ag from substrate to film, which otherwise can segregate into the grain boundaries and make the films non-superconducting.