Theoretical and Experimental Identification of Seeds Number on the Crystal Morphology and Physical Properties of GdBCO Bulks by Gd+011 TSIG Process

It is well known that single- and multiple-domain REBCO bulks can be fabricated with single seed and multiple seeds by the top-seeded melt textured growth and top-seeded infiltration and growth processes. Some results indicate that the physical properties are better for single-domain REBCO bulks, but some others show that the physical properties are better for multiple-domain REBCO bulks, which is true? In order to make clear this contrary results and what is really happening for the single- and multiple-domain REBCO bulks, we have theoretical analyzed the crystal morphologies and experimental investigated the single- and multiple-domain GdBCO samples based on the crystal morphology of GdBCO bulk, the result indicates that: 1) the thickness of the multiple domain in the GdBCO bulks is decreasing with the increasing number of the seeds, while the thickness of the pure c-axis domain is increasing with the increasing number of the seeds; 2) if the sample is thinner, the pure c-axis domain is not so important, so the more the seeds, the more number of the multiple domain and grain boundaries in the GdBCO bulk, and the weaker the physical properties; and 3) if the sample is thicker, the pure c-axis domain is very important, so the more the seeds, the thinner of the multiple domain and the thicker of the pure c-axis domain in the GdBCO bulk, and the better the physical properties.