THE GROWTH-MECHANISM OF A LA-DOPED Y1BA2CU3O7-Y CRYSTAL PREPARED BY AMELT PROCESS

The growth behaviour of a Y123 crystal was investigated in a melt-text ured Y0.75La0.25Ba2Cu3O7-y specimen in which La had been substituted f or Y. A chi-shaped pattern, which is likely to be related to the cryst al orientation, was observed. The concentration of Y and La atoms vari ed gradually from the centre to the surface of the grains. The growth pattern of a La-doped Y123 crystal, which is very similar to the annua l rings of a tree, was explained by a solubility difference between Y and La atoms in a melt that in turn led to the different formation tem perature of a La-doped Y123 crystal.