Abstract
The crystal growth of YBCO (123:YBa_2Cu_3O_<7-x>) superconductive oxide under an external electric field has been investigated by means of in-situ observations and differential thermal analysis. The growth process of YBCO crystal via a peritectic reaction, i.e., 211(Y_2BaCuO_5) + liquid → YBCO (123), is differentiated into (1) dissolution of the 211 phase into solution, (2) transportation process of the solute, Y(Y_2O_3), in the liquid, (3) nucleation and (4) kinetic attachment of the solute to the growth front. Each process was modified by an external electric field of 600 V/cm which turned into an electric field as large as 10^4 to 10^5 V/cm occurring in an electric double layer forming at the solid-solution interface ; however, almost no electric field could be generated in the bulk liquid due to it being electrically conductive. The external electric field enhanced dissolution of the 211 gains, but had almost no effective electric field operated on the transportation process of the solute, and little effect was observed on the solute attachment kinetics. On the other hand, the external electric field increased the critical energy for the nucleation of the YBCO grains, which retarded the nucleation of the YBCO grains.
