SIMULATED GROWTH AND MICROSTRUCTURE OF DYBA2CU3O7-X WITH AND WITHOUT DY2BACUO5 ADDITION

We present optical observations of magnetically melt-textured DYBa2Cu3O7-x with and without 20 wt. % excess of Dy2BaCuO5. From these observations, we propose some kinetic mechanism of the growth of 123 compounds. Kinetic processes can be simulated on computers. Two (very) simple models derived from the well-known Eden model are presented. They simulate the growth of the grain front. The simulated patterns agree with the observations. The microstructure of such materials cannot be explained by thermodynamic and chemical considerations alone, but explanations must include the kinetics of the growth front as well. From our observations, we conclude that the growth probability ratios g(110)/g(100) and g(100)/g(001) are of the order of 10 and 50, respectively.