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

Abstract Dysprosium barium niobate has been developed as a new substrate suitable for both YBa 2 Cu 3 O 7− δ (YBCO) and (Bi,Pb) 2 Sr 2 Ca 2 Cu 3 O x [Bi(2223)] superconductor films. DyBa 2 NbO 6 (DBNO) has a cubic perovskite (A 2 BB′O 6 ) structure with a lattice constant a =8.456 A. DBNO was found to have a thermal expansion coefficient of 7.806×10 −6 °C −1 and a thermal conductivity 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 microwave applications. Both YBCO and Bi(2223) superconductors did not show any detectable chemical reaction with DBNO even under extreme processing conditions. Dip-coated YBCO thick film on polycrystalline DBNO substrate gave a T c (0) of 92 K and J c of ∼1.1×10 4 A cm −2 . Bi(2223) thick film dip-coated on DBNO gave T c (0) of 110 K and J c of ∼4×10 3 A cm −2 .