Formation of BaCeO₃ and its influence on microstructure of sintered/melt-textured Y-Ba-Cu-O oxides with CeO₂ addition

The formation of BaCeO₃ and its effects on microstructure were studied in sintered/melt-textured Y-Ba-Cu-O oxides containing 5 wt. % CeO₂ and various amounts of Y₂Ba₁Cu₁O₅. The added CeO₂ was converted to fine particles of BaCeO₃ near 930 °C, which is the conventional sintering temperature for Y-Ba–Cu-O. Y₂Ba₁Cu₁O₅ and CuO are formed as by-products of the reaction between CeO₂ and Y₁Ba₂Cu₃O_7−y phase. The CeO₂ addition reduced the particle size of Y₂Ba₁Cu₁O₅ which was trapped in the Y₁Ba₂Cu₃O_7−y matrix after the melt-texture growth. During the peritectic decomposition stage of Y₁Ba₂Cu₃O_7−y phase into Y₂Ba₁Cu₁O₅ and liquid phase, the morphology of the decomposed Y₂Ba₁Cu₁O₅ was changed from a blocky shape in the undoped sample to an acicular shape of high anisotropy in the CeO₂-added sample. The formation of the highly anisotropic Y₂Ba₁Cu₁O₅ particles appears to be responsible for the refinement of Y₂Ba₁Cu₁O₅ particle after the melt-texture processing.