Ba(2)RETaO(6) (RE=Pr, Nd, Eu, and Dy), a group of chemically stable substrates for YBa2Cu3O7-delta films

A group of complex perovskites, Ba(2)RETaO(6) (where RE = Pr, Nd, Eu, and Dy) has been synthesised and sintered as single phase materials with high sintered density and stability by solid state reaction. All compounds were found to be isostructural, having a complex cubic perovskite crystal structure of the general formula A(2)(BB')O-6 with the lattice constant value in the range from 8.55 to 8.44 Angstrom, The values of the dielectric constant and the loss factor for these materials are in the range suitable for the use as substrates for microwave applications of superconductor films, The YBa2Cu3O7-delta superconductor showed no chemical reaction with Ba(2)RETaO(6) ceramics even when they were mixed in composites of the form 80 vol% YBCO-20 vol% Ba(2)RETaO(6) and processed in air up to 1223 K, All the composites showed a T-c(0) of 92 K. The YBCO thick films fabricated on polycrystalline Ba(2)RETaO(6) specimens by dip coating and partial melting techniques showed (00l) orientation with T-c(0 of 92 K. (C) 1996 Academic Press, Inc.