Flux Pinning Analysis of Superconducting YBCO Foam Struts

Magnetization loops were measured on struts of superconducting YBa
₂
Cu
₃
O
_x
(YBCO, 123-phase) foams taken from various positions of a 5 × 2 × 2 cm
³
large foam sample prepared at RWTH Aachen. From these data, flux pinning forces, F
_p
= j
_c
× B, were calculated and pinning force scaling diagrams F
_p
/F
_p,max
versus h = H
_a
/H
_irr
were established. The scaling in the temperature range 60 K ≤ T ≤ 85 K was found to be well developed for all samples with peak positions, h
₀
, above 0.4, which is an indication of δT
_c
pinning. From microstructure analysis using the electron backscatter diffraction technique (EBSD), it is known that the struts are fully converted into the 123-phase with embedded 211 particles being relatively small. The variation of Fp depending on the position of the struts in the original sample directly reveals the changes of the texture as found employing EBSD.