Ba_2 GdTaO_6, a ceramic substrate for Yba_2Cu_3O_7-δ films

摘要

The ceramic Ba_2GdTaO_6 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 A. The values of dielectric constant and loss factor for Ba_2 GdTaO_6 specimens are moderately low and are comparable to those of MgO for its use as substrate for microwave applications of superconducting films. The superconducting Yba_2Cu_3O_7-δ (YBCO) remained chemically stable with Ba_2 GdTaO_6 even under severe heat treatment, and the supercon- Ducting properties of YBCO are unaffected by the addition of Ba_2 GdTaO_6 up to 20 vol/100 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 Ba_2 GdTaO_6 as a suitable substrate for Yba_2Cu_3O_7-δ superconducting films.