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MgO template layer, containing a much smaller domain size, may not afford the sub-grain
boundary development in a colony structure. The difference in the domain size between MgO and
YSZ can then result in the distinctly different inter-grain connectivity observed in YBCO films
grown on the two template layers.
Figure 2(a) Dark field TEM image showing the domain structure in the MgO template layer. The
bright contrast regions are oriented within 50 of the diffracted beam. (b) Corresponding SAD
pattern showing the strong <001> texture and the average in-plane misorientation.
CONCLUSION
The microstructure of YBCO films grown on IBAD YSZ and MgO template layers has been
characterized by TEM. The distinctly different microstructure and the inter-grain connectivity can
be linked to the different domain size in the template layers. The overall misorientation angles of
the two templates are similar in magnitude, however, on the microscopic level, the YSZ sample has
a much larger domain size than MgO. The larger the domain size, the easier it will be to form
colonies consisting of well-aligned YBCO grains. Hence, the difference in microstructure of the
template layers can influence the grain connectivity and microstructure of the YBCO layers.
REFERENCES
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3. S.R. Foltyn et al., International Workshop on Superconductivity Proceedings, Hawaii, 68
(1997).