This comprehensive survey deals with the melt-growth process and characterization of the novel class of ternary materials, (Nd,Sm,Gd)Ba2Cu3Oy 'NSG-123'. Microstructure observations by optical microscopy, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) revealed the presence of sub-micron secondary phase (RE2BaCuO5, 211) particles uniformly dispersed in the 123 matrix that enhance flux pinning at low fields and improve the performance of this material. The energy-resolved TEM-EDX analysis clarified that small particles consist mainly of Gd2BaCuO5 'Gd-211', irrespective of the initially added secondary phase (Gd-211 or NSG-211). Dark-field TEM observations showed that the NSG-123 matrix had a high density of RE-rich RE1+xBa2-xCu3Oy (RE-123ss) clusters 3-10 nm in size. These small clusters enhance pinning at intermediate fields. The scaling analyses of the volume pinning force density at 77 K made on NSG-123 samples with varying 211 contents of various secondary phases showed the secondary peak at normalized fields as high as 0.45, which might indicate the activation of ΔTc pinning mechanism. Trapped field measurements proved that silver was the key element to improve the mechanical strength of NSG-123 materials. Record trapped-field values at high magnetic fields can be obtained at 77 K with appropriately large sized NSG-123 samples.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Physics and Astronomy (miscellaneous)
- Condensed Matter Physics