Es. Reddy et T. Rajasekharan, Melt processing and microstructural analysis of GdBa(2)Cu(3)Oy with varying amounts of Gd2BaCuO5 phase, J MATER SCI, 34(15), 1999, pp. 3755-3767
Bulk samples of GdBa2Cu3Oy (Gd-123) with varying amount of Gd2BaCuO5 (Gd-21
1) phase are melt processed. The processing conditions and the resulting ma
cro and microstructures were discussed. The T-c of the material is found to
be sensitive to the processing atmosphere, and the percentage of 211 in th
e precursor powder. Pure Gd-123 samples behaved differently as compared to
the compositions with excess 211 phase. The amount of porosity and the aver
age size of pores in the samples decreases with the increasing amount of Gd
-211 in the precursor powder. The densification of the melt textured materi
al is ascribed to the densification process of the precursors prior to the
texturing stage. Irrespective of the Gd-211 content macro-cracks within dom
ains were observed in parallel to the intrinsic micro-cracks. At the meltin
g stage refinement of the Gd-211 particles originating from the decompositi
on 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. (C) 1999 Kluwer Academic Publishers.