Superconductivity at 52 K in iron based F doped layered quaternary compound Pr[O_1–xF_x]FeAs

Since the discovery of copper oxide superconductor in 1986 [1], extensive efforts have been devoted to the search of new high-T c superconducting materials, especially high-T c systems other than cuprates. The recently discovered quaternary superconductor La[O 1-x F x ]FeAs with the superconducting critical transition T c of 26 K [2], which has a much simple layered structure compared with cuprates, has attracted quick enthusiasm and is going to become a new high-T c system [3-6]. Here we report the discovery of bulk superconductivity in the praseodymiumarsenide oxides Pr[O 1-x F x ]FeAs with an onset drop of resistivity as high as 52 K, and the unambiguous zero-resistivity and Meissner transition at low temperature, which will place these