Growth Mechanism of RE-Ba-Cu-O Crystal by Liquid Phase Epitaxy Process

Abstract

ABSTRACTGrowth of YBa2Cu3Oy (YBCO) crystals both on the MgO and the YBCO substrates has been investigated in order to clarify the growth mechanism of the liquid phase epitaxy (LPE) process for the coated conductor. It was found that the slope angle of the growth grain varied with growing in the initial stage of the LPE growth. In the case of the MgO substrate, the slope angle increased with laterally growing the crystal. On the other hand, the slope angle decreased with growing the crystal in the case of the YBCO substrate. This phenomenon with the opposite tendency could be explained by considering the difference in the step-advancing rates between on the MgO and the YBCO surfaces. It was found that the deep and steep valley of the LPE grains due to the slow step-advancing rate on the MgO is the origin of the flux trapping inclusions. It is necessary that the seed films should cover the entire MgO surface without undesired orientation grains and impurity particles in order to obtain the high quality LPE layer.