Studies on Ba/sub 2/YNbO/sub 6/ buffer layers for subsequent YBa/sub 2/Cu/sub 3/O/sub 7-x/ film growth

In this paper, we are reporting a dielectric oxide buffer Ba/sub 2/YNbO/sub 6/ (BYNO) and its performance on various substrates for a potential buffer layer for the growth of YBa/sub 2/Cu/sub 3/O/sub 7-x/ (YBCO) coated conductors. Ba/sub 2/YNbO/sub 6/ is a moderate dielectric. Using pulsed laser deposition, epitaxial BYNO films were grown at 850/spl deg/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 /spl sim/8/spl deg/ and thickness of these layers /spl sim/100 nm on metal substrates. Highly c-axis oriented YBCO films were deposited on BYNO buffered substrates. Critical transition temperatures (T/sub c0/) determined from electrical transport measurements vary between 88-89 K and corresponding critical current densities (J/sub c/) ranging from 0.5-1 MA/cm/sup 2/ at 77 K.