Modelling of orientation relations in 2-D percolative systems of buffered metallic substrates for coated conductors

The crystallographic alignment of various layers of high T/sub c/ coated conductors has been studied in detail using X-Ray Diffraction (XRD) and Electron BackScatter Diffraction (EBSD). Several possible configurations of buffer layers on NiFe substrates are considered, including metallic buffers (Pd/Ag) and native oxides (NiFe/sub 2/O/sub 4/) as well as the more widely studied ceramic buffer route(CeO/sub 2//YSZ). The surface texture data (EBSD) was compared with bulk texture measurements (XRD) in order to assess the relationship between them. The percolative properties of the grain structure were investigated using a two dimensional hexagonal grain model, which considers both in-plane and out-of-plane grain boundary misorientations. The model was extended to consider critical currents of macroscopic samples. Factors which affect the percolative nature of current flow in superconducting coated conductors, such as grain size and tape dimensions, have also been studied.