Melt processing and microstructural analysis of GdBa2Cu3Oy with varying amounts of Gd2BaCuO5 phase


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Abstract

Bulk samples of GdBa2Cu3Oy (Gd-123) with varying amount of Gd2BaCuO5 (Gd-211) phase are melt processed. The processing conditions and the resulting macro and microstructures were discussed. The Tc of the material is found to be sensitive to the processing atmosphere, and the percentage of 211 in the precursor powder. Pure Gd-123 samples behaved differently as compared to the compositions with excess 211 phase. The amount of porosity and the average size of pores in the samples decreases with the increasing amount of Gd-211 in the precursor powder. The densification of the melt textured material is ascribed to the densification process of the precursors prior to the texturing stage. Irrespective of the Gd-211 content macro-cracks within domains were observed in parallel to the intrinsic micro-cracks. At the melting stage refinement of the Gd-211 particles originating from the decomposition of Gd-123 was observed with the increasing amounts of external Gd-211 in the liquid. The quantitative analysis of the microstructural features, i.e., the residual Gd-211, platelet width, domain sizes of the resulting melt textured materials were presented. Addition of Ag resulted in mild refining of 211 particles.

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