Multiseeded melt growth of bulk Y-Ba-Cu-O using thin film seeds

Y-Ba-Cu-O (YBCO) and Sm-Ba-Cu-O thin films have been used for the first time as heterogeneous seeds to multiseed successfully the melt growth of bulk YBCO in a multiseeded melt growth process. The use of thin film seeds, which may be prepared with highly controlled orientation (i.e., with a well-defined a-b plane and precisely known a-direction), is based on their superheating properties and reduces significantly contamination of the bulk sample by the seed material. A variety of grain boundaries were obtained by varying the angle between the seeds. Microstructural studies indicate that the extent of residual melt deposited at the grain boundary decreases with increasing grain boundary contact angle. It is established that the growth front proceeds continuously at the (110)/(110) grain boundary without trapping liquid, which leads to the formation of a clean grain boundary.