Studies on Ba2YNbO6 buffer layers for subsequent YBa2Cu3O7-x film growth

In this paper, we are reporting a dielectric oxide buffer Ba₂YNbO₆ (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa₂Cu₃O_7-x (YBCO) coated conductors. Ba₂YNbO₆ is a moderate dielectric. Using pulsed laser deposition, epitaxial BYNO films were grown at 850°C with an oxygen pressure of 200 mTorr on single crystal MgO (100) substrate and ion beam assisted sputter deposited MgO buffered hastelloy metal substrates. The surface morphology of the BYNO films reveals out growths even though the average surface roughness is only 2-8 nm. The texture of BYNO films is ∼8° and thickness of these layers ∼100 nm on metal substrates. Highly c-axis oriented YBCO films were deposited on BYNO buffered substrates. Critical transition temperatures (T_c0) determined from electrical transport measurements vary between 88-89 K and corresponding critical current densities (J_c) ranging from 0.5-1 MA/cm² at 77 K.