MICROSTRUCTURAL STUDY OF THE EFFECT OF AN EXCESS OF Y2BACUO5 AND BASNO3 DOPING ON THE TEXTURING PROCESS OF YBA2CU3O7-X BULK SUPERCONDUCTORS

Melt texture process of YBCO leads to a YBa2Cu3O7-x matrix where Y2BaC uO5 particles are observed. The Y2BaCuO5 inclusions size and distribut ion depend upon several parameters: YBa2Cu3O7-x grain size in the pres intered, heating rate, dopants. The influence of an excess of Y2BaCuO5 and/or BaSnO3 on these Y2BaCuO5 particles are observed in the liquid phase and in the texture domain. According to the dopant used, two kin ds of coarsening of Y2BaCuO5 can be observed: an isotropic and an anis otropic. The control of the distribution of Y2BaCuO5 particle size is of primary interest to improve the efficiency of the MTG process. In p articular large cooling rate (5 degrees C/h) during the texture format ion could be used by adding Y2BaCuO5 + BaSnO3 to YBa2Cu3O7-x compositi on.