Development and Dielectric Properties of Ba2−xSrxDyTaO6(x=0, 1, and 2) Substrates for YBa2Cu3O7−δFilms

A group of complex perovskites Ba2−xSrxDyTaO6(wherex=0, 1 and 2) was synthesized, sintered, and developed. These ceramics were found to be isostructural, having a complex cubic perovskite crystal structure ofA2(BB′)O6-type compounds, and the values of lattice constant were in the range 0.826 to 0.844 nm. The moderately low values of dielectric constant and loss factor for Ba2−xSrxDyTaO6ceramics are in the range suitable for their use as substrates for microwave applications of superconducting films. The value of dielectric constant decreased with increasing strontium content for barium. The superconducting YBCO showed no chemical reaction with these ceramics under severe heat treatment and the superconducting properties of YBCO were unaffected by the addition of 20 vol% substrate material in YBCO in the form of composites. The YBCO thick films fabricated on ceramic Ba2−xSrxDyTaO6specimens by dip-coating and partial melting techniques were textured, showing (00l) orientation with aTc(0)of 90 K. Plate-like and needle-like grain growth over a wide area of thick films was observed by SEM studies.