Ba2GdTaO6, a ceramic substrate for YBa2Cu3O7-delta films

The ceramic Ba2GdTaO6 has been developed as a single phase material with high sintered density and stability by solid state reaction method. It exhibited a complex cubic perovskite of A(2)(BB')O-6-type crystal structure with a lattice constant of 8.47 Angstrom. The values of dielectric constant and loss factor for Ba2GdTaO6 specimens are moderately low and are comparable to those of MgO for its use as substrate for microwave applications of superconducting films. The superconducting YBa2Cu3O7-delta (YBCO) remained chemically stable with Ba2GdTaO6 even under severe heat treatment, and the superconducting properties of YBCO are unaffected by the addition of Ba2GdTaO6 up to 20 vol% in YBCO in the form of composites. Fabrication of YBCO thick films with superconducting zero resistance transition, T-c(o) of 90 K demonstrated the use of Ba2GdTaO6 as a suitable substrate for YBa2Cu3O7-delta superconducting films.