The microstructural features of the (Nd,Eu,Gd)Ba2Cu3O7 (NEG) bulks were studied by optical microscopy in polarized light. The quantitative microstructural data were obtained using the image processing system, Image-Pro Plus. Unlike YBa2Cu3Oy, melt-processed bulks, the NEG bulk superconductors prepared by oxygen-controlled-meltgrowth process do not exhibit macroscopic 211 secondary-phase inhomogeneity due to 211 particle pushing. The lowering of interface energy and increase of melt viscosity are suggested to be responsible for the essential suppression of 211 pushing in NEG melt-grown bulks. This result opens a way to achieve a homogeneous distribution of the current densities in melt-grown bulk superconductors.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics
- Energy Engineering and Power Technology
- Electrical and Electronic Engineering