Superconductivity at 38 K in Iron-Based Compound with Platinum–Arsenide Layers Ca10(Pt4As8)(Fe2-xPtxAs2)5

We report superconductivity in novel iron-based compounds Ca-10(PtnAs8)(Fe2-xPtxAs2)(5) with n = 3 and 4. Both compounds crystallize in triclinic structures (space group P (1) over bar), in which Fe2As2 layers alternate with PtnAs8 spacer layers. Superconductivity with a transition temperature of 38K is observed in the n = 4 compound with a Pt content of x similar or equal to 0: 36 in the Fe2As2 layers. The compound with n = 3 exhibits superconductivity at 13 K.