Electron Microprobe Characterization of Melt-Textured YBCO Created Using Hybrid Powder Metallurgy

An YBCO monolith was created by conventional top-seeded melt-texture processing using a mixture of Y and YBa₂Cu₃O_7-delta (Y123) powders. The composition of the bulk monolith thus lies in the Y-Ba-Cu oxide ternary system rather than on the binary join between Y123 and Y₂BaCuO₅ (Y211) and the liquid line of descent, therefore, differs from the peritectic one exhibited by Y211-Y123 mixtures. In particular, Y123 crystallizes over a temperature interval that may be as large as 50degC and from a liquid with a considerable range in Cu content. Y123 in the Y-Y123 monolith exhibits a range in composition, particularly in Cu content that we ascribe to the change in crystallization conditions. This allows the spatial pattern of crystallization of the monolith to be mapped. Crystallization commenced at the seed crystal but then appears to have moved to the outer parts of the monolith before ending in the interior of the sample.