Fabrication, Characterization and Study of MOD Multi-Layer YBCO Films

Fabrication of thick YBa
₂
Cu
₃
O
_y
(YBCO) films with high critical current densities(J
_c
) has remained one of the major challenges in the coated conductor development process. In this work, we report successful fabrication of several multi-layer YBCO films with thicknesses ranging from 0.1 micrometers to 1.2 micrometers. The films were deposited on a single crystal substrate by using a multi-layer TFA-MOD technique. The effect of variation in the thickness of an individual layer in a multi-layer film on the overall properties of the film was studied by processing multi-layer films with individual layers of 0.1 micrometers, 0.2 micrometers and 0.5 micrometers. The J
_c
value for the 0.1 micrometers thick single-layer film was as high as 7 MA/cm
²
, and the J
_c
for 6-layer1.2 micrometers thick film was 1 MA/cm
²
at 77 K and self field. XRD, SEM and TEM were used to study the dependence of J
_c
on the orientation, texture and microstructure of the film. It was found that the texture, connections between the two successive layers, porosity, and the crack formation affect the J
_c
of the film. In addition, we report a multi layer fabrication route with a shorter duration of the pyrolysis reaction according to the number of coats.