A polished cross-section of a typical quenched semisolid zone of a single crystal 123 filament is shown below. The polycrystalline precursor fiber can be seen to the left. Between the semisolid zone and the precursor fiber is a swollen section formed when the barium cuprate liquid in the zone wicks up into the polycrystalline precursor. The interface between the growing single crystal and the semisolid zone can be seen to the right. During solidification, the 211 phase in the semisolid zone dissolves and acts as a yttrium source for the growing 123 crystal. The 211 particles which are not completely dissolved are incorporated into the 123 single crystal matrix. The LHFZ growth process can be used to prepare single crystal filaments of YBCO materials for growth rates below approximately 2 cm/h. Higher growth rates produce crystals with more than one grain.
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©CPRL, 1995