Synthesis and Superconducting Properties of the Iron Oxyarsenide TbFeAsO0.85

The iron oxyarsenide TbFeAsO 0.85 was synthesized by a high-pressure method. A high-quality polycrystalline sample was obtained and characterized by measurements of magnetic susceptibility and electrical resistivity. Bulk superconductivity with T c of 42 K was clearly established without an F doping usually conducted to tune on superconductivity in the iron oxypnictide system.