MASS-TRANSFER IN A ERBA2CU3O7 PELLET PARTIALLY MELTED IN A THERMAL-GRADIENT

Melt texturing in high thermal gradients promotes the crystallization of oriented RBa2Cu3Ox grains which improves the critical current densities. However, the presence of high thermal gradients induces a transport of material that modifies the composition of the melt and disrupts the crystallization process. In this study, material transfer phenomena have been examined by crystallizing a ErBa2Cu3Ox pellet in a static thermal field. The influence of material transfer on the microstructure of textured pellets has been studied. These microstructures indicate that the material is transferred mainly by thermocapillarity. We also determined that the temperature of the characteristic ridge formed during crystallization was about 892 +/- 10-degrees-C which corresponds closely to the solidification of the binary and ternary eutectic temperatures.