Iron-based layered superconductor La[O1-xFx]FeAs (x=0.05-0.12) with Tc=26 K

We report that a layered iron-based compound LaOFeAs undergoes superconducting transition under doping with P ions at the O2- site. The transition temperature (T-c) exhibits a trapezoid shape dependence on the F- content, with the highest T. of similar to 26 K at -11 atom %.