High rate melt texturing of Nd1-xBa2+xCu3O7-delta type superconductors

Melt texturing is one of the most prominent techniques available to fabricate bulk high-temperature superconductors with superior current transport and magnetic properties. In the case of Y1Ba2Cu3Ox, melt textured samples can have a J(c) on the order of 10(5) A/cm(2) at 77 K and zero applied magnetic field, and in excess of 10(3) A/cm(2) at 77 K and 30 T. However, a serious drawback of the melt textured Y1Ba2Cu3Ox compound, which severely restricts its application, is the very slow rate (1 mm/h) needed to develop the highly textured planar front necessary for optimum superconducting properties. RE-123 compounds containing the rare earth element neodymium have been recently found to recrystallize much more rapidly, indicating the possibility of their high speed melt texturing. By processing bars (50 mmX5 mmX5 mm) of these compounds through a high-temperature gradient, fully textured microstructures were obtained at rates up to 50 mm/h, which are more than 50 times faster than those employed in Y1Ba2Cu3Ox. After oxygen annealing, these textured bars have a T-c onset of 93 K and a transport J(c), at 77 K and zero applied magnetic field, on the order of 5000 A/cm(2). These results are expected to increase significantly as more progress takes place. (C) 1996 American Institute of Physics.