Transport properties and microstructure of mono- and seven-core wires of   FeSe1-xTex superconductor by Fe-diffusion powder-in-tube method
  We report the successful fabrication of mono- and seven-core superconducting wires of FeSe1-xTex using an in-situ Fe-diffusion process based on the powder-in-tube (Fe-diffusion PIT) method. The reacted layer in these wires were found to have composite structure with composition nearly FeSe and FeTe for the inner and outer layers, although a single layer of composition FeSe0.5Te0.5 was supposed to be formed. The self-field transport Jc values at 4.2 K were found to be 226.2 A/cm2 and 100.3 A/cm2 respectively for mono- and seven-core wires. The Jc's of mono- and seven-core wires dropped rapidly at low fields and then showed a gradual decrease with increasing magnetic fields. In addition, the seven-core wire showed higher Jc than the mono-core wire under higher magnetic fields, indicating that the seven-core wire of FeSe1-xTex superconductor using Fe-diffusion PIT method is advantageous for the superconducting-wire application under high magnetic fields. 
Toshinori Ozaki, Keita Deguchi, Yoshikazu Mizuguchi, Yasuna Kawasaki,   Takayoshi Tanaka, Takahide Yamaguchi, Shunsuke Tsuda...
cond-mat.supr-con