Superconductivity at 15 K in NdFe0.9Rh0.1AsO without F-doping

We present results of transport and magnetic properties measurements performed on polycrystalline NdFe0.9Rh0.1AsO. Despite the large size difference between Fe and Rh elements, this compound undergoes a superconducting transition with T-c similar to 15 K. We have compared the transport properties of this Rh-doped oxypnictide with that of optimally doped NdFeAsO0.88F0.12 Contrary to this latter compound, a strong upturn of the normal-state resistivity occurs above T-c, and no peak of the thermopower has been observed. (C) 2009 Elsevier B.V. All rights reserved.