Critical currents and microstructures of LPE grown YBCO bicrystal films with large single facet grain boundaries

The microstructures and electric transport properties across grain boundari es (GBs) are studied for YBaCuO bicrystal films grown by liquid phase epita xy (LPE) method. Large single facet GBs with typical size of 10-100 mu m ar e obtained in the films on MgO bicrystal substrates. Microstructures and at omic arrangements of GBs with different misorientation angles upsilon are i nvestigated by TEM. The critical current densities across [001] tilt GBs as a function of upsilon show that J(c) values are almost constant up to simi lar to 12 degrees and then decrease exponentially, as usually observed for bicrystal films grown by physical vapor deposition methods. The presence of a plateau region up to 12 degrees demonstrates a feature of the clean and meandering free GB structure in the LPE bicrystal films. The temperature an d field dependencies of I-c for 24 degrees GB are presented and discussed b ased on the microstructures. (C) 2000 Elsevier Science B.V. All rights rese rved.