Homologous series of iron pnictide oxide superconductors (Fe2As2)x[Can+1(Sc,Ti)nOy] (n=3,4,5) with extremely thick blocking layers

We have discovered homologous series of iron pnictide superconductors (Fe2As2)[Can+1(Sc,Ti)(n)O-y] (n=3,4,5). These compounds have extremely thick blocking layers up to quintuple perovskite layers sandwiched by the Fe2As2 layers. These samples exhibited bulk superconductivity with relatively high T-c up to 42 K. The relationship between T-c and the iron-plane interlayer distance suggested that T-c of the iron based superconductor is basically determined by the local structure of Fe2As2 layer. (C) 2010 American Institute of Physics. [doi:10.1063/1.3478850]