Thick Secondary Phase Pinning-Enhanced YBCO Films on Technical Templates

The critical current I
_c
(B) of YBa
₂
Cu
₃
O
_7-δ
(YBCO) coated conductors can be increased by growing thicker superconductor layers as well as improving the critical current density J
_c
(B) by the incorporation of artificial pinning centers. We studied the properties of pulsed laser deposited BaHfO
₃
(BHO)doped YBCO films with thicknesses of up to 5 μm on buffered rolling-assisted biaxially textured Ni-5 at% W tape and alternating beam assisted deposition textured Yttrium-stabilized ZrO
₂
layers on stainless steel. X-Ray diffraction confirms the epitaxial growth of the superconductor on the buffered metallic template. BHO additions reduce the film porosity and lower the probability to grow misoriented grains, hence preventing the J
_c
decrease observed in undoped YBCO films with thicknesses >2 μm. Thereby, a continuous increase in I
_c
at 77 K is achieved. A mixed structure of secondary phase nanorods and platelets with different orientations increases J
_c
(B) in the full angular range and simultaneously lowers the J
_c
anisotropy compared to pristine YBCO.