Synthesis and physical properties of Ca1-xRExFeAs2 with RE = La ~ Gd
  Synthesis of a series of layered iron arsenides Ca1-xRExFeAs2 (112) was attempted by heating at 1000 C under a high-pressure of 2 GPa. The 112 phase successfully forms with RE = La, Ce, Nd, Sm, Eu and Gd, while Tb, Dy and Ho substituted and RE free samples does not contain the 112 phase. The Ce, Nd, Sm, Eu and Gd doped Ca1-xRExFeAs2 are new compounds. All of them exhibit superconducting transition except for the Ce doped sample. The behaviour of the critical temperature, with the RE ionic radii have been investigated. 
Alberto Sala, Hiroyuki Yakita, Hiraku Ogino, Tomoyuki Okada, Akiyasu   Yamamoto, Kohji Kishio, Shigeyuki Ishida, Akira Iyo, ...
cond-mat.supr-con