Effect of twins in Ni substrates on the microstructure of La2Zr2O7 films for coated conductors

Abstract

La2Zr2O7 (LZO) films were deposited by chemical solution deposition on Ni95Wi5rolling assisted bi-axially textured substrates to be used in YBa2Cu3O7 (YBCO) coated conductors. These LZO films were proved of good qualities for YBCO deposition by metal organic chemical vapor deposition that is an economic process. The mosaic of LZO films is only slightly degraded by the process of grain-to-grain epitaxial transfer (16% with respect to that of the substrate). The film is composed of small crystallites (20–40nm) and larger anomalous crystallites (100–400nm) found in great number in transferred twins from the substrate. The anomalous crystallites are poorly crystallized or amorphous and contain more C than areas with normal crystallites. High temperature in-situ X-ray diffraction shows a sudden crystallization at 860°C that does not seem to involve a solid state reaction. The anomalous crystallites are analyzed to result from a locally enhanced barrier to nucleation and might reveal poor characteristics of the crystallization.