Abstract
The microstructure and the flux pinning capability of SiO
2
-added YBa
2
Cu
3
O
y
thick films on Ag substrates were investigated. A series of YBa
2
Cu
3
O
y
thick films with small amounts (0–0.5 wt%) of nano-sized SiO
2
particles (12 nm) was prepared. The thicknesses of the prepared thick films was approximately 100 µm. Phase analysis by x-ray diffraction and microstructure examination by scanning electron microscopy were performed and the critical current density dependence on the applied magnetic field J
c
(H) and electrical resistivity ρ(T) were investigated. The magnetic field and temperature dependence of the critical current density (J
c
) was calculated from magnetization measurements using Bean’s critical state model. The results showed that the addition of a small amount (≤0.02 wt%) of SiO
2
was effective in enhancing the critical current densities in the applied magnetic field. The sample with 0.01 wt% of added SiO
2
exhibited a superconducting characteristics under an applied magnetic field for a temperature ranging from 10 to 77 K.