Synthesis of superconducting films and improvement of their flux pinning properties with barium zirconate nanoparticles using chemical solution deposition method

The present thesis demonstrates synthesis and characterization of BZO doped YBCO and GdBCO superconducting thin films on STO and LAO single crystal substrates using chemical solution deposition technique for high magnetic field applications. With this respect, transparent solutions were prepared both from commercially available YBCO powder and metal acetates seperately by using different types of solvents as methanol, ethanol and propionic acid. Contact angle values of these solutions on STO and LAO substrates were determined to estimate their wettability features. A detailed rheological characterization was performed to determine shear profile and scrutinize effect of temperature on viscosity. The solutions were spin coated on the substrates and heat treated according to the profile. Thermal, microstructural and electrical properties of BZO doped superconducting thin films were determined through DTA-TG, FTIR, XRD, SEM-EDS, AFM, inductive critical transition temperature, inductive critical current density and transport measurements. The results show that six mol percentage BZO doped YBCO samples on both substrates possess the highest critical current density value for all magnetic fields. Additionally, GdBCO superconducting thin films exhibit higher critical transition temperature and self-field critical current density values in comparison to the YBCO films. According to the measurement results of GdBCO samples, the twelve mol percentage BZO doped GdBCO sample on STO substrate possess the highest critical current density value for all magnetic fields. These results indicate that the BZO dopant in the structure act as artificial pinning centers and increased the current carrying capability of films in magnetic field conditions.