Development and characterisation of dysprosium barium niobate: a new substrate for YBa2Cu3O7-delta and (Bi,Pb)(2)Sr2Ca2Cu3Ox superconductor films

Dysprosium barium niobate has been developed as a new substrate suitable fo r both YBa2Cu3O7-delta (YBCO) and (Bi, Pb)(2)Sr2Ca2Cu3Ox [Bi(2223)] superco nductor films. DyBa2NbO6 (DBNO) has a cubic perovskite (A(2)BB'O-6) structu re with a lattice constant a = 8.456 Angstrom. DBNO was found to have a the rmal expansion coefficient of 7.806 X 10(-6)degrees C-1 and a thermal condu ctivity of 67.9 W m(-1) K-1. The dielectric constant and loss factor values of DBNO are also in a range suitable for its use as substrate for microwav e applications. Both YBCO and Bi(2223) superconductors did not show any det ectable chemical reaction with DBNO even under extreme processing condition s. Dip-coated YBCO thick film on polycrystalline DBNO substrate gave a T-c( 0) of 92 K and J(c) of similar to 1.1 X 10(4) A cm(-2). Bi(2223) thick film dip-coated on DBNO gave T-c(O) of 110 K and J(c) of similar to 4 X 10(3) A cm(-2). (C) 1999 Elsevier Science B.V. All rights reserved.