Growth, Microstructure, and Properties of GdBCO–Ag Superconductor

We prepared GdBa
₂
Cu
₃
O
_7-δ
(Gd123, GdBCO) single-grain bulk with Ag addition via the top-seeded melt growth method. Peritectic temperatures of precursor powder mixture and pure Gd123 powder were tested by differential thermal analysis (DTA). The dependence of the volume fraction and the size of Gd
₂
BaCuO
₅
(Gd211) particles on the distance from the seed was determined with the help of image processing of the micrographs taken by a scanning electron microscope (SEM) from the polished a/c-section of the sample. The morphology of Ag particles was evaluated by the SEM image analysis. The substitution of Ag in Gd123 was characterized by the wavelength-dispersive spectrometry. The magnetic measurements of superconducting properties (critical current density J
_c
at 77 K and critical temperature T
_c
) were carried out using a vibrating sample magnetometer. Magnetization measurements were performed on the specimens taken from several different locations of the same crystal plane and the value of the maximum middle critical temperature (T
_c,m
) was determined as 92.6 K.