Transport properties of an engineered [001] tilt series in bu bicrystals

Single grain boundaries (GB’s) of an engineered [001] tilt series of bulk (Formula presented)(Formula presented)(Formula presented) (YBCO) bicrystals were electrically characterized to probe the intrinsic and extrinsic factors influencing GB properties of bulk melt-processed (MP) YBCO. The bicrystal series ranged from 1.5° to 45° misorientation angle and displayed tendencies similar to those of thin film GB’s at 77 K in self-field. Subtle differences between thin film and bulk GB transport behavior that were observed may be attributed to the thin film substrate. The dependence of normal-state resistance ((Formula presented)) at 77 K on the [001] tilt angle has been noted. An anticorrelation between (Formula presented) and critical current ((Formula presented)) exists such that the product, (Formula presented), of each bicrystal from 10° to 45° falls within a narrow band of 10 to 20 μV. Such a narrow characteristic voltage range suggests highly reproducible growth conditions. It is also reasonable to suggest that naturally grown boundaries in bulk MP YBCO have more uniform GB character than their thin film counterparts. This advantageous growth technique allows us to further probe the role of the GB plane in influencing transport properties.