Enhancement of transport critical current density of SmFeAsO1-xFx tapes   fabricated by an ex-situ powder-in-tube method with a Sn-presintering process
  SmFeAsO1-xFx (Sm1111) tapes were prepared by an ex-situ powder-in-tube method with a Sn-presintering process. Scanning electron microscopy revealed apparent difference in microstructure between Sn-presintered tapes and the previously reported polycrystalline Sm1111 bulk, since Sn has reduced FeAs wetting phase and filled the voids between Sm1111 grains. The Sn-presintered tapes showed significant enhanced field dependences of transport Jc compared with Sn-added tapes. A highest transport critical current density (Jc) of 3.45x10^4 A cm-2 at 4.2 K and self-field is achieved. Magneto-optical (MO) imaging further confirmed large and well-distributed global and intergranular Jc in Sn-presintered Sm1111 tapes. 
Qianjun Zhang, Chao Yao, He Lin, Xianping Zhang, Dongliang Wang,   Chiheng Dong, Pusheng Yuan, Shaopu Tang, Yanwei Ma, Satos...
cond-mat.supr-con