Synthesis of ErFeAsO-based superconductors by the hydrogen doping method
National Institute of Advanced Industrial Science and Technology - Tsukuba, Ibaraki 305-8568, Japan
2 Department of Applied Electronics, Tokyo University of Science - Noda, Chiba 275-8510, Japan
3 JST, Transformative Research-Project on Iron Pnictides (TRIP) - 5, Sanbancho, Chiyoda, Tokyo 102-0075, Japan
Accepted: 19 November 2010
Here we demonstrate the technique to stabilize the ErFeAsO-based superconductor with the smallest lattice constants in LnFeAsO1−y (Ln = lanthanide) series using the hydrogen doping method. Polycrystalline samples were synthesized by heating pellets with nominal compositions of ErFeAsO1−y (1−y = 0.75–0.95) sandwiched between pellets of LaFeAsO0.8H0.8 compositions at 1100 °C under a pressure of 5.0–5.5 GP. The sample with lattice constants, a = 3.8219 Å and c = 8.2807 Å, shows the highest superconducting critical temperatures (Tc), 44.5 K and 41.0 K, determined by onset transitions of resistivity and susceptibility, respectively. We discuss the phase diagram of the Ln-dependence of Tc in LnFeAsO-based superconductors.
PACS: 74.70.Xa – Pnictides and chalcogenides / 74.25.F – Transport properties / 74.25.Dw – Superconductivity phase diagrams
© EPLA, 2010