Various kinds of microstructures exist in the c-axis oriented bicrystal YBa2Cu3O7–δ films grown by liquid phase epitaxy, which had an important effect on the properties of the bicrystal junctions. Distinct configurations of the bicrystal boundary near to the bicrystal substrate were observed directly. The cross-sectional view of different kinds of bicrystal films provided a platform for the study of the mechanism of single-crystal growth. Furthermore, Mg diffusion, introduced by the MgO substrates, was also studied by using a transmission electron microscope equipped with an energy dispersive spectrometer. Grain boundaries in the seed layer, and then grain boundaries in the liquid-phase epitaxial layer, acted as important channels for Mg diffusion.

Microstructure and Magnesium Diffusion in YBa2Cu3O7–δ Films on Bicrystal MgO Substrates. Z.Hao, Y.Wu, Y.Enomoto, K.Tanabe, N.Koshizuka: Journal of Applied Physics, 2002, 91[11], 9251-4