Influence of Zr- and Sn-Doping on Sm-Ba-Cu-O Filaments Fabricated by a Chemical Solution Spinning

The effect of Zr and Sn addition on the critical current density (J
_c
) and the microstructure of filamentary SmBa
₂
Cu
₃
O
_y
(Sm123) has been investigated. Samples with additions fabricated by a solution spinning method were partially melted under an atmosphere gas containing 0.1-3.0% O
₂
. After heat-treatment, homogeneous dispersion of fine Sm
₂
BaCuO
₅
(Sm211) particles was observed in the Zr-doped sample. The 0.2 at% Zr-doped Sm123 showed the depressed J
_c
value of 1.8 × 10
⁴
at 77 K and self-field compared with the undoped sample. From the J
_c
measurement in magnetic fields, J
_c
value higher than 10
³
A/cm
²
at 77 K was maintained up to 8 T. On the other hand, 0.2 at% Sn-added sample showed high J
_c
value of 5.0 × 10
⁴
A/cm
²
at 77 K and self-field, and the J
_c
value higher than 10
³
A/cm
²
is maintained up to 17 T. A small amount of Sn doping was found to be effective in increasing the J
_c
under high magnetic field and the irreversibility field of Sm123 filaments.