A new quenching technique was used for detailed microstructural examination of quenched YBa 2 Cu 3 O 61d ͞liquid interfaces. The examination revealed that the growth rate and the amount of excess Y 2 BaCuO 5 (211) had a strong influence on the growth morphology of YBa 2 Cu 3 O 61d (123). The maximum growth rate at which single crystal growth could be obtained increased from 1 mm͞s to 1.5 mm͞s as excess 211 content increased from 0 to 20 wt. %. It then decreased to 1 mm͞s as excess 211 increased

more »

... to 40 wt. %. Dendritic growth with distinguishable secondary arms occurred for stoichiometric 123 samples in the regime of cellular/dendritic growth. A highly curved 123 envelope was formed on 211 particles located at the 123 growth interface for stoichiometric 123 samples in the regime of single crystal growth. The microscopic 123 growth interface became flat as excess 211 content increased to 20 wt. %. The engulfment of 211 particles into 123 matrix is discussed based on detailed microstructural examination. It is found that the formation of a small highly curved 123 envelope on 211 particles for stoichiometric 123 samples is due to the large 211 particle spacing.